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<div> (3) Merger with Nuvelo, Inc. on January 27, 2009 On January 27, 2009, the Company completed the Merger, with ARCA Colorado in accordance with the terms of the Merger Agreement, in which a wholly-owned subsidiary of Nuvelo merged with and into ARCA Colorado, with ARCA Colorado continuing after the Merger as the surviving corporation and a wholly-owned subsidiary of Nuvelo. Immediately following the Merger, the Company changed its name from Nuvelo, Inc. to ARCA biopharma, Inc., and its common stock began trading on the Nasdaq Global Market under the symbol "ABIO" on January 28, 2009. On March 7, 2011, the listing of the Company's common stock was transferred from the Nasdaq Global Market to the Nasdaq Capital Market. The Merger was treated as a reverse merger and accounted for as a business combination using the acquisition method of accounting in accordance with ASC 805. For accounting purposes, ARCA Colorado was considered to have acquired Nuvelo in the Merger, as the stockholders of ARCA Colorado prior to the Merger had a controlling interest in the combined company and the Company's management is the former management of ARCA Colorado. Pursuant to the rules and regulations of the United States Securities and Exchange Commission, or the SEC, the historical financial statements of ARCA Colorado replaced the historical financial statements of Nuvelo, and the disclosures in this report relating to the pre-Merger business of the Company, unless noted as being the business of Nuvelo prior to the Merger, pertain to the business of ARCA Colorado prior to the Merger. The estimated total acquisition consideration of $11.9 million to acquire Nuvelo was based on the market capitalization of Nuvelo as of January 27, 2009 and the estimated fair values of its vested stock options and warrants outstanding on that date, as this was deemed the most reliable measure of the consideration effectively transferred to acquire Nuvelo on that date. The Company estimated the net assets acquired in the Merger to be $37.2 million, including $45.5 million of cash, cash equivalents and marketable securities. In accordance with ASC 805, any excess of fair value of net assets acquired in a business combination over the acquisition consideration results in a gain on bargain purchase, and as a result, the Company recorded a gain on bargain purchase of $25.3 million. </div>

<div> (1) The Company and Summary of Significant Accounting Policies Description of Business ARCA biopharma, Inc., or the Company or ARCA, a Delaware corporation, is headquartered in Broomfield, Colorado and is a biopharmaceutical company principally focused on developing genetically-targeted therapies for cardiovascular diseases. The Company's lead product candidate, GencaroTM (bucindolol hydrochloride), a pharmacologically unique beta-blocker and mild vasodilator, is being developed for the treatment and the prevention of atrial fibrillation, or AF, in patients with heart failure, or HF. The Company has identified common genetic variations in the cardiovascular system that it believes interact with Gencaro's pharmacology and may predict patient response to Gencaro treatment. The Company has been granted patents in the U.S., Europe, and other jurisdictions for methods of treating AF and HF patients with Gencaro based on genetic testing, which it believes will provide market exclusivity for these uses of Gencaro into at least 2026 in the U.S. and into 2025 in Europe. In addition, the Company believes that if Gencaro is approved, the Gencaro patents will be eligible for patent term extension based on our current clinical trial plans which, if granted in the U.S., may provide market exclusivity in the U.S. into 2029, and if granted in Europe may provide market exclusivity into 2030. The Company is planning to initiate a Phase 3 clinical study of Gencaro in AF patients with HF and/or left ventricular dysfunction. The Company believes AF is an attractive indication for Gencaro because data from the previously conducted Phase 3 HF trial of Gencaro in 2,708 HF patients, or the BEST HF trial, suggest that Gencaro may have a potentially significant effect in reducing or preventing AF. Based on the BEST HF trial, the Company believes that Gencaro's prevention of AF in HF patients is pharmacogenetically regulated. The Company plans to enroll approximately 200-400 patients with persistent AF who have the genotype that appears to respond most favorably to Gencaro. The Company anticipates that the AF trial could begin approximately 6 months after the Company obtains sufficient funding. To support the continued development of Gencaro, including the planned AF clinical trial and ongoing operations, the Company will need to raise substantial additional funding through public or private debt or equity transactions or a strategic combination or partnership, or government funding. ARCA also holds exclusive patent rights to other product candidates that have potential indications in cardiovascular disease, oncology and other therapeutic areas, some of which are in early stages of development and others of which are in later stages of development. The Company is seeking partners to assist it in the development of these candidates or who may license them. For example, ARCA holds exclusive rights to rNAPc2, a recombinant protein that is a potent, long acting tissue factor inhibitor with a unique mechanism of action. Previously, preclinical studies of rNAPc2 showed evidence of potential efficacy against lethal hemorrhagic fever viruses. Development Stage Risks, Liquidity and Going Concern The Company is in the development stage and devotes substantially all of its efforts towards obtaining regulatory approval, exploring strategic alternatives for further developing Gencaro, and raising capital necessary to fund its operations. The Company has not generated revenue to date and is subject to a number of risks similar to those of other development stage companies, including dependence on key individuals, the development of and regulatory approval of commercially viable products, the need to raise adequate additional financing necessary to fund the development and commercialization of its products, and competition from larger companies. The Company has historically funded its operations through issuances of convertible promissory notes and shares of its common and preferred stock, as well as through the business combination with Nuvelo, Inc, or Nuvelo.   Since ARCA was founded on December 17, 2001, or Inception, the Company has incurred substantial losses and negative cash flows from operations. Since Inception, the Company incurred a loss from operations of $94.8 million and had negative cash flows from operations of $93.3 million. In light of the substantial additional time and costs associated with the development of Gencaro and the need to raise a significant amount of capital on acceptable terms to finance the additional clinical trial and the Company's ongoing operations, the Company is evaluating strategic alternatives for funding continued operations and development programs. The Company will need to complete a strategic transaction, such as a strategic combination or partnership, or raise substantial additional funding through public or private debt or equity securities, or government funding to support the continued development of Gencaro, including the additional clinical trial. In 2011, the Company raised $4.0 million, net of offering costs, through the sales of our common stock and may seek additional funding that could allow it to operate while it continues to pursue strategic combination, partnering, additional financing and licensing opportunities. If the Company is delayed in completing or is unable to complete additional funding and/or a strategic transaction, the Company may discontinue its development activities or discontinue its operations. The Company currently believes its cash and cash equivalents balance as of December 31, 2011 will be sufficient to fund its operations through September 30, 2012. The Company is unable to assert that its current cash and cash equivalents are sufficient to fund operations beyond that date, and as a result, there is substantial doubt about the Company's ability to continue as a going concern beyond September 30, 2012. These consolidated financial statements have been prepared with the assumption that the Company will continue as a going concern and will be able to realize its assets and discharge its liabilities in the normal course of business and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from the inability of the Company to continue as a going concern. The Company may not be able to raise sufficient capital on acceptable terms, or at all, to continue development of Gencaro or to otherwise continue operations and may not be able to execute any strategic transaction. The Company's liquidity, and its ability to raise additional capital or complete any strategic transaction, depends on a number of factors, including, but not limited to, the following:   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> the costs and timing for the planned AF clinical trial in order to gain possible FDA approval for Gencaro; </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> the market price of the Company's stock and the availability and cost of additional equity capital from existing and potential new investors; </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> the Company's ability to retain the listing of its common stock on the Nasdaq Capital Market; </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> general economic and industry conditions affecting the availability and cost of capital; </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> the Company's ability to control costs associated with its operations; </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> the costs of filing, prosecuting, defending and enforcing any patent claims and other intellectual property rights; and </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> the terms and conditions of the Company's existing collaborative and licensing agreements. </td></tr></table> The sale of additional equity or convertible debt securities would likely result in substantial additional dilution to the Company's stockholders. If the Company raises additional funds through the incurrence of indebtedness, the obligations related to such indebtedness would be senior to rights of holders of the Company's capital stock and could contain covenants that would restrict the Company's operations. The Company also cannot predict what consideration might be available, if any, to the Company or its stockholders, in connection with any strategic transaction. Should strategic alternatives or additional capital not be available to the Company in the near term, or not be available on acceptable terms, the Company may be unable to realize value from its assets and discharge its liabilities in the normal course of business which may, among other alternatives, cause the Company to further delay, substantially reduce or discontinue operational activities to conserve its cash resources.   Merger with Nuvelo, Inc. On January 27, 2009, the Company completed a business combination, or the Merger, with ARCA Colorado in accordance with the terms of that Agreement and Plan of Merger and Reorganization, dated September 24, 2008, and amended on October 28, 2008 (as amended, the "Merger Agreement"), in which a wholly-owned subsidiary of Nuvelo merged with and into ARCA Colorado, with ARCA Colorado continuing after the Merger as the surviving corporation and a wholly-owned subsidiary of Nuvelo. Immediately following the Merger, the Company changed its name from Nuvelo, Inc. to ARCA biopharma, Inc. The business combination is treated as a reverse merger for accounting purposes, and ARCA Colorado is the accounting acquirer, and the entity formerly known as Nuvelo, Inc. is the acquired company ("Nuvelo"). Pursuant to the rules and regulations of the United States Securities and Exchange Commission, or the SEC, the historical financial statements of ARCA Colorado replaced the historical financial statements of the acquired company, and the disclosures in this report relating to the pre-Merger business of the Company, unless noted as being the business of Nuvelo prior to the Merger, pertain to the business of ARCA Colorado prior to the Merger. See Note 3 for further discussion of the Merger. Merger Exchange Ratio and Reverse Stock Split In conjunction with and immediately prior to the Merger, Nuvelo effected a 1 for 20 reverse stock split. As a result, and in accordance with the Merger Agreement, each outstanding common share and warrant or option to purchase ARCA Colorado's common stock prior to the Merger was converted into the right to receive or purchase 0.16698070, or the Exchange Ratio, shares of the Company's common stock, which Exchange Ratio incorporates the effect of the reverse stock split. All common shares, options and warrants to purchase common shares and per common share amounts for all periods presented in the accompanying financial statements and notes have been adjusted retroactively to reflect the effect of the Exchange Ratio, except for the par value per share and the number of shares authorized, which are not affected by the Exchange Ratio. The accompanying consolidated financial statements and notes have not been adjusted to retroactively reflect the effect of the Exchange Ratio on preferred shares, warrants to purchase preferred shares, and per preferred share amounts. Basis of Presentation The Company has generated no revenue to date and its activities have consisted of seeking regulatory approval, research and development, exploring strategic alternatives for further developing and commercializing Gencaro, and raising capital. Accordingly, the Company is considered to be in the development stage at December 31, 2011. Accounting Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. The Company bases estimates on various assumptions that are believed to be reasonable under the circumstances. The Company believes significant judgment was involved in estimating the fair value of assets acquired and liabilities assumed in the Merger, including in-process research and development, facility exit costs, clinical trial accruals, and in estimating other accrued liabilities, stock-based compensation, and income taxes. Additionally, significant estimates and judgment are required in the evaluation of in-process research and development for impairment. Management is continually evaluating and updating these estimates, and it is possible that these estimates will change in the future or that actual results may differ from these estimates. Cash Equivalents Cash equivalents generally consist of money market funds and debt securities with maturities of 90 days or less at the time of purchase. The Company invests its excess cash in securities with strong ratings and has established guidelines relative to diversification and maturity with the objective of maintaining safety of principal and liquidity.   The Company classifies all cash equivalents as available-for-sale securities, and records investments at fair value. Unrealized holding gains and losses on available-for-sale securities, net of any tax effect, are excluded from earnings and are reported in accumulated other comprehensive income (loss), a separate component of stockholders' equity, until realized. The specific identification method is utilized to calculate the cost to determine realized gains and losses from the sale of available-for-sale securities. Realized gains and losses are included in interest income in the consolidated statements of operations. Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents and other receivables. The Company has no off-balance-sheet concentrations of credit risk, such as foreign exchange contracts, option contracts, or foreign currency hedging arrangements. The Company maintains cash and cash equivalent balances in the form of bank demand deposits, money market fund accounts and debt securities with financial institutions that management believes are creditworthy. Such balances may at times exceed the insured amount. Property and Equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Cost includes expenditures for equipment, leasehold improvements, replacements, and renewals. Maintenance and repairs are charged to expense as incurred. When assets are sold, retired, or otherwise disposed of, the cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in operations. The cost of property and equipment is depreciated using the straight-line method over the estimated useful lives of the related assets. Leasehold improvements are amortized over the shorter of the life of the lease or the estimated useful life of the assets. Property and equipment acquired in the Merger were recorded at the estimated fair value as of the date of the Merger, and are subsequently depreciated using the straight-line method over the estimated remaining useful lives of the related assets. Long-Lived Assets and Impairments The Company reviews long-lived assets whenever events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. As a development stage company, the Company has not generated positive cash flows from operations, and such cash flows may not materialize for a significant period in the future, if ever. Additionally, the Company may make changes to its business plan that would result in changes to expected cash flows from long-lived assets. It is reasonably possible that future evaluations of long-lived assets, including changes from the Company's current expected use of long-lived assets, may result in material impairments. Accrued Expenses As part of the process of preparing its financial statements, the Company is required to estimate accrued expenses. This process involves identifying services that third parties have performed on the Company's behalf and estimating the level of service performed and the associated cost incurred for these services as of the balance sheet date. Examples of estimated accrued expenses include contract service fees, such as fees payable to contract manufacturers in connection with the production of materials related to the Company's drug product, and professional service fees, such as attorneys, consultants, and clinical research organizations. The Company develops estimates of liabilities using its judgment based upon the facts and circumstances known at the time. Segments The Company operates in one segment. Management uses one measure of profitability and does not segment its business for internal reporting.   Research and Development Research and development costs are expensed as incurred. These consist primarily of salaries, contract services, and supplies. Costs related to clinical trial and drug manufacturing activities are based upon estimates of the services received and related expenses incurred by contract research organizations, or CROs, clinical study sites, drug manufacturers, collaboration partners, laboratories, consultants, or otherwise. Related contracts vary significantly in length, and could be for a fixed amount, a variable amount based on actual costs incurred, capped at a certain limit, or for a combination of these elements. Activity levels are monitored through communications with the vendors, including detailed invoices and task completion review, analysis of expenses against budgeted amounts, and pre-approval of any changes in scope of the services to be performed. Certain significant vendors may also provide an estimate of costs incurred but not invoiced on a periodic basis. Expenses related to the CROs and clinical studies are primarily based on progress made against specified milestones or targets in each period. Stock-Based Compensation The Company's stock-based compensation cost recognized includes: (a) compensation costs for current period vesting of all share-based awards granted prior to January 1, 2006, based on the intrinsic value method, and (b) compensation cost for current period vesting of all share-based awards granted or modified subsequent to January 1, 2006, based on the estimated grant date fair value. The Company recognizes compensation costs for its share-based awards on a straight-line basis over the requisite service period for the entire award, as adjusted for expected forfeitures. From Inception through December 31, 2005, the Company accounted for issuances of stock-based compensation under the intrinsic-value-based method of accounting. Under this method, compensation expense is generally recorded on the date of grant only if the estimated fair value of the underlying stock exceeds the exercise price. Income Taxes The current provision for income taxes represents actual or estimated amounts payable or refundable on tax returns filed or to be filed each year. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date. The overall change in deferred tax assets and liabilities for the period measures the deferred tax expense or benefit for the period. The measurement of deferred tax assets may be reduced by a valuation allowance based on judgmental assessment of available evidence if deemed more likely than not that some or all of the deferred tax assets will not be realized. The Company has recorded a valuation allowance against its deferred tax assets, as management has concluded that it is more likely than not that the net deferred tax asset will not be realized through future taxable income, based primarily on the Company's history of operating losses. As a result of the Merger, a change of ownership of Nuvelo per Internal Revenue Code Section 382 occurred, and accordingly, the Company's ability to utilize Nuvelo's pre-Merger net operating loss carryforwards has been substantially reduced. </div>

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<div> (8) Collaborative Agreements Archemix In July 2006, Nuvelo entered into a collaboration agreement with Archemix Corporation, or Archemix. Under the agreement, Archemix was responsible for the discovery of short-acting aptamers targeting the coagulation cascade for use in acute cardiovascular procedures, and the Company was responsible for development and worldwide commercialization of these product candidates. In August 2006, Nuvelo made an upfront license fee payment to Archemix of $4.0 million, and pursuant to the terms of the agreement committed to funding at least $5.25 million of Archemix's research over the first three years of the agreement. As of July 2009, this funding commitment had been satisfied. Archemix had the right to receive payments totaling up to $35.0 million per development compound contingent upon the achievement of specified development and regulatory milestones, along with potential royalty payments based on sales of licensed compounds. In February 2008, Nuvelo paid Archemix a $1.0 million milestone fee that was accrued upon dosing of the first patient in the Phase 1 trial for NU172. On April 20, 2010, the Company amended its collaboration agreement with Archemix for the discovery and development of novel aptamers with anti-coagulation activities, or the Amended Agreement. In the Amended Agreement, the parties modified certain financial provisions and certain other provisions to reflect the termination of the research and collaboration and limitation of the agreement to NU172. In summary, the agreement was amended, as follows:   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> Pursuant to the previous agreement, ARCA funded a research collaboration under which Archemix generated candidate aptamers for ARCA's selection for further development and commercialization. In the Amended Agreement, ARCA is given sole control over the development, manufacture and commercialization of NU172, and no further research or development collaboration is provided for. </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> Under the previous agreement, for each product resulting from the collaboration, ARCA had the obligation to fund the development and commercialization of such product and pay milestones and royalties to Archemix on the net sales for such product. However, Archemix had the option to share in 25% of the expenses incurred and profits obtained from the development and commercialization of such product, which election Archemix could make after the inception of the Phase 3 clinical trial for the product. In the Amended Agreement, Archemix no longer has such participation right, but will have the right to receive milestones and royalties on the net sales of NU172, if any, on the same terms and conditions as those under the previous agreement. </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> The Amended Agreement revises the exclusivity provision to provide that Archemix will not, by itself or in collaboration with a third party, develop, manufacture or commercialize short-acting aptamers that directly inhibit thrombin or are used as a treatment for viral or bacterial infections, and in either case cause a therapeutically-useful level of anticoagulation. </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> Pursuant to the previous agreement, ARCA had the obligation to purchase Archemix common stock in an Archemix initial public offering under certain conditions and subject to certain terms. In the Amended Agreement, this obligation is eliminated.</td></tr></table> </div>

<div> (7) Commitments and Contingencies The Company has or is subject to the following commitments and contingencies: Employment Agreements The Company maintains employment agreements with several key executive employees. The agreements may be terminated at any time by the Company with or without cause upon written notice to the employee, and entitle the employee to wages in lieu of notice for periods not exceeding one calendar year from date of termination without cause or by the employee for good reason. Certain of these agreements also provide for payments to be made under certain conditions related to a change in control of the Company. Operating Leases The Company is party to a lease agreement, dated February 8, 2008. The original lease provided for approximately 15,000 square feet of an office facility in Broomfield, Colorado, which serves as the Company's primary business offices. The lease has a term of five years with rights to extend the term for two additional three year periods. On June 14, 2011, the Company entered into a first amendment (the "Amendment") to the lease agreement. Under the terms of the Amendment, the Company and its landlord mutually agreed for the Company to relocate from its previous office suite of approximately 15,000 square feet, to another suite within the same building, comprising approximately 4,500 square feet. The office location continues to serve as the Company's primary business office. The Amendment also modified the annual per square foot rate of rent and allows the Company to terminate with three months notice. As part of the agreement, the Company made a one-time payment to the landlord of $200,000, which the landlord agreed to use for the landlord's improvements in the new leased premises prior to the Company occupying the space. The original five year term of the Lease remains unchanged. Per the lease agreement, base rent is subject to annual increases of approximately three percent per year. The rent expense for the lease is being recognized on a straight-line basis over the lease term. Under the original lease, the Company received tenant improvement reimbursements from the landlord totaling $593,000 which were recorded as deferred rent and were amortized as reductions to rent expense. The $200,000 payment made to the landlord in conjunction with the Amendment was recorded against the existing deferred rent balance. The net deferred rent balance is being amortized as reductions to rent expense over the remaining term of the lease. The unamortized deferred rent balance as of December 31, 2011 was $49,000. Rent expense under this lease for the years ended December 31, 2011 and 2010 was $150,000 and $123,000, respectively, and was $459,000 from Inception through December 31, 2011. Below is a summary of the future minimum lease payments committed under Company's facility in Broomfield, Colorado as of December 31, 2011 (in thousands):   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="68%" align="center"> <tr><td width="89%"> </td> <td valign="bottom" width="7%"> </td> <td> </td> <td> </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> 2012</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">81</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> 2013</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">40</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Total future minimum rental payments</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">121</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr></table> University of Cincinnati In April 2011, the Company entered into a license agreement with the University of Cincinnati to license exclusive worldwide rights to a portfolio of U.S. and international patents, which includes certain U.S. and international diagnostic patents covering genetic markers for ARCA's lead drug candidate, Gencaro. These patents provide the basis for exclusive worldwide development, use and commercialization of the genetic test which may indicate a patient's likely response to Gencaro as a treatment for chronic HF, AF, and other indications. Under the terms of the agreement, ARCA agreed to pay the University of Cincinnati annual license fees and is obligated to future milestone payments for each United States patent issued subsequent to the date of the agreement. The agreement also requires royalty payments on net sales from genetic testing performed expressly for the purpose of prescribing bucindolol. Laboratory Corporation of America In February 2007, the Company entered into a commercialization and licensing agreement with Laboratory Corporation of America, or LabCorp, to develop, make, market and sell diagnostic tests in connection with the medical prescription of the Company's lead compound, Gencaro. Under the agreement the Company has licensed to LabCorp certain rights to commercialize a diagnostic test. The license agreement has a term of 10 years. LabCorp has the right to cancel the agreement and give the rights to the diagnostic back to the Company. In addition, the Company granted to LabCorp 16,698 shares of common stock. The shares are subject to a restricted stock agreement in which shares vest upon the attainment of certain regulatory approval and drug product sales milestones. Cardiovascular Pharmacology and Engineering Consultants, LLC, or CPEC Under the terms of its strategic license agreement with CPEC, a licensing subsidiary of Indevus Pharmaceuticals Inc. (a wholly owned subsidiary of Endo Pharmaceuticals), holding ownership rights to certain clinical trial data of Gencaro, the Company will incur milestone and royalty obligations upon the occurrence of certain events. In August 2008, the Company paid CPEC a milestone payment of $500,000 based on the July 31, 2008 submission of its NDA with the FDA. If the FDA grants marketing approval for Gencaro, the Company will owe CPEC another milestone payment of $8.0 million, which is due within six months after FDA approval. The Company also has the obligation to make milestone payments of up to $5.0 million in the aggregate upon regulatory marketing approval in Europe and Japan. The Company's royalty obligation ranges from 12.5% to 25% of revenue from the related product based on achievement of specified product sales levels, including a 5% royalty that CPEC is obligated to pay under its original license agreement for Gencaro. The Company has the right to buy down the royalties to a range of 12.5% to 17% by making a payment to CPEC within six months of regulatory approval. Dendreon In February 2004, Nuvelo obtained exclusive worldwide rights to all indications of rNAPc2 and all other rNAPc molecules owned by Dendreon Corporation as a result of a licensing agreement entered into with them. Under the terms of the agreement, Nuvelo paid Dendreon an upfront fee of $4.0 million ($0.5 million in cash and $3.5 million in Nuvelo common stock) in 2004. Future milestone payments to Dendreon could reach as much as $2.5 million if rNAPc2 is successfully developed and all commercialization milestones are achieved for the indication of treatment for Ebola virus infection. In addition, such milestones could reach as much as $23.5 million if rNAPc2 is developed and commercialized for indications other than Ebola virus infection. ARCA currently cannot predict if or when any of these milestones will be achieved. If rNAPc2 is commercialized, ARCA will be responsible for paying royalties to Dendreon based on sales of rNAPc2. </div>

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<div> (11) Stock-based Compensation Warrants As of December 31, 2011, warrants to purchase 2,750,151 shares of common stock were outstanding at exercise prices ranging from $1.485 to $19.48, with a weighted average exercise price per share of $2.65. These warrants, which were granted as part of various financing and business agreements, expire at various times between October 2013 and August 2018. Warrants were recorded in additional paid-in capital at their estimated fair market value at the date of grant using the Black-Scholes option-pricing model. Stock Plans The Company's equity incentive plan was amended, as approved by shareholders on June 25, 2009, to (i) change the name of the plan from the Amended and Restated Nuvelo, Inc. 2004 Equity Incentive Plan to the Amended and Restated ARCA biopharma, Inc. 2004 Equity Incentive Plan, or the Equity Plan, (ii) increase the maximum number of shares issuable under the plan, revise the formula for determining the maximum number of shares issuable under the plan and implement new share usage rules; and (iii) adjust the award limitations for stock options and stock appreciation rights. As a result of such amendment, the maximum number of shares issuable under the Equity Plan was increased by 326,323 shares. The Equity Plan provides for the granting of stock options (including indexed options), stock appreciation rights, restricted stock purchase rights, restricted stock bonuses, restricted stock units, performance shares, performance units and deferred stock units. Under the Equity Plan, awards may be granted to employees, directors and consultants of ARCA, except for incentive stock options, which may be granted only to employees. As of December 31, 2011, options to purchase 393,345 shares were outstanding under the Equity Plan, and 506,908 shares were reserved for future awards. In general, the Equity Plan authorizes the grant of stock options that vest at rates set by the Board of Directors or the Compensation Committee thereof. Generally, stock options granted by ARCA under the equity incentive plans become exercisable ratably for a period of three to four years from the date of grant and have a maximum term of ten years. The exercise prices of stock options under the equity incentive plan generally meet the following criteria: the exercise price of incentive stock options must be at least 100% of the fair market value on the grant date and exercise price of options granted to 10% (or greater) stockholders must be at least 110% of the fair market value on the grant date. ARCA's other stock plans under which options remained outstanding as of December 31, 2011 are the Non-Employee Director Stock Option Plan. As of December 31, 2011, options to purchase 914 shares were outstanding under this stock plan. In conjunction with the Merger, the Company discontinued grants under its 2004 Stock Option Plan effective January 27, 2009. As of December 31, 2011, options to purchase 469,979 shares with a weighted average exercise price of $2.38 per share were outstanding under this plan. Options and awards outstanding under this plan will continue to vest according to the original terms of each grant. No new awards will be granted under this plan. Subsequent to the Merger, the Company has granted stock-based compensation awards under the Equity Plan. The Company granted options to purchase 164,700 and 128,170 shares of common stock in the years ended December 31, 2011 and 2010, respectively. The fair values of employee stock options granted in the years ended December 31, 2011 and 2010 were estimated at the date of grant using the Black-Scholes model with the following assumptions and had the following estimated weighted average grant date fair value per share:   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="76%" align="center"> <tr><td width="69%"> </td> <td valign="bottom" width="14%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="13%"> </td> <td> </td> <td> </td> <td> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="6" align="center">Years Ended December 31,</td> <td valign="bottom"> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">2011</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">2010</td> <td valign="bottom"> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Expected term</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">5.8 years</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">5.7 years</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Expected volatility</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">110</td> <td valign="bottom" nowrap="nowrap">% </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">86</td> <td valign="bottom" nowrap="nowrap">% </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Risk-free interest rate</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">2.20</td> <td valign="bottom" nowrap="nowrap">% </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">2.70</td> <td valign="bottom" nowrap="nowrap">% </td></tr> <tr><td valign="top"> Expected dividend yield</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">0</td> <td valign="bottom" nowrap="nowrap">% </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">0</td> <td valign="bottom" nowrap="nowrap">% </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Weighted-average grant date fair value per share</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">1.83</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">2.04</td> <td valign="bottom" nowrap="nowrap">  </td></tr></table> A summary of ARCA's stock option activities for the years ended December 31, 2011 and 2010, and related information as of December 31, 2011, is as follows:   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%" align="center"> <tr><td width="63%"> </td> <td valign="bottom" width="4%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="4%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="4%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="4%"> </td> <td> </td> <td> </td> <td> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="14" align="center">For the years ended December 31,</td> <td valign="bottom"> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="6" align="center">2011</td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="6" align="center">2010</td> <td valign="bottom"> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center"># of Options</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">Weighted Average Exercise Price</td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center"># of Options</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">Weighted Average Exercise Price</td> <td valign="bottom"> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Options outstanding, beginning of period</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">953,238</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">31.87</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">921,104</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">69.60</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Granted</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">164,700</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">2.24</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">128,170</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">2.95</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Exercised</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(1,126</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">1.31</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(49,487</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">2.80</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Forfeited and cancelled</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(252,574</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">110.81</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(46,549</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">729.70</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Options outstanding, end of period</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">864,238</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">3.20</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">953,238</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">31.87</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> Options exercisable, end of period</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">616,148</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">3.35</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">676,972</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">43.49</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Options vested and expected to vest</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">847,425</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">3.21</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr></table> The total intrinsic value of options exercised for the years ended December 31, 2011 and 2010 was $1,000 and $208,000, respectively. As of December 31, 2011, the unrecognized compensation expense related to unvested options, excluding estimated forfeitures, was $ 464,000, which compensation expense is expected to be recognized over a weighted average period of 1.8 years. The Company recognizes compensation costs for its share-based awards on a straight-line basis over the requisite service period for the entire award, as adjusted for expected forfeitures.   The following table summarizes information about stock options outstanding and exercisable as of December 31, 2011:   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%" align="center"> <tr><td width="32%"> </td> <td valign="bottom" width="9%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="9%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="9%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="9%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="9%"> </td> <td> </td> <td> </td> <td> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="10" align="center">Options Outstanding</td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="6" align="center">Options Exercisable</td> <td valign="bottom"> </td></tr> <tr><td valign="bottom" nowrap="nowrap" align="center">   Range of Exercise Prices  </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">Number Outstanding</td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">Weighted Average Remaining Contractual Term (in years)</td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">Weighted Average Exercise Price</td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">Number Exercisable</td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">Weighted Average Exercise Price</td> <td valign="bottom"> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> $  0.06  -  $   0.60</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">7,488</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">3.42</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">0.52</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">7,488</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">0.52</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top">     0.90  -       0.90</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">203,065</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">4.83</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">0.90</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">203,065</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">0.90</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top">     1.68  -       1.86</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">100,093</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">5.90</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">1.83</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">95,829</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">1.83</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top">     2.24  -       2.24</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">164,700</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">9.38</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">2.24</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">32,017</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">2.24</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top">     2.69  -       2.90</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">167,895</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">6.93</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">2.82</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">109,765</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">2.83</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top">     2.97  -       5.57</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">217,208</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">7.26</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">4.63</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">164,195</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">4.74</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top">   14.58  -   318.00</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">3,789</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">4.00</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">143.19</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">3,789</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">143.19</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr> <tr><td valign="top"> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">864,238</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">6.82</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">3.20</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">616,148</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">3.35</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr></table> For the years ended December 31, 2011 and 2010 and for the period from Inception through December 31, 2011, the Company recognized the following non-cash, share-based compensation expense (in thousands):   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="84%" align="center"> <tr><td width="65%"> </td> <td valign="bottom" width="8%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="8%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="8%"> </td> <td> </td> <td> </td> <td> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="6" nowrap="nowrap" align="center">Years Ended December 31,</td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom" colspan="2" nowrap="nowrap" align="center">Period from December 17, 2001 (date of inception) to December 31,</td> <td valign="bottom"> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">2011</td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">2010</td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">2011</td> <td valign="bottom"> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Research and Development</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">117</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">128</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">496</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Selling, General and Administrative</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">191</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">330</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">1,399</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Restructuring Expense</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">387</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> Total</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">308</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">458</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">2,282</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr></table> Stock-based compensation expense related to non-employees was negligible in 2011 and 2010. ARCA did not recognize any tax benefit related to employee stock-based compensation cost as a result of the full valuation allowance on its net deferred tax assets. </div>

781000

-781000

-0.99

-0.53

<div> (2) Earnings (Loss) Per Share The Company calculates basic earnings per share by dividing (loss) earnings attributable to common stockholders by the weighted average common shares outstanding during the period, excluding common stock subject to vesting provisions. Diluted earnings per share is computed by dividing (loss) attributable to common stockholders by the weighted average number of common shares outstanding during the period increased to include, if dilutive, the number of additional common shares that would have been outstanding if the potential common shares had been issued. The Company's potentially dilutive shares include options and warrants.   A reconciliation of the numerator and denominator used in the calculation of basic and diluted loss per share follows:   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%" align="center"> <tr><td width="76%"> </td> <td valign="bottom" width="7%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="7%"> </td> <td> </td> <td> </td> <td> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="6" align="center">Years Ended December 31,</td> <td valign="bottom"> </td></tr> <tr><td valign="bottom">(In thousands, except shares and per share data)</td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">2011</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">2010</td> <td valign="bottom"> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Net loss</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">(5,364</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">(8,420</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> Net loss available to common shareholders</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">(5,364</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">(8,420</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Weighted average shares of common stock outstanding</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">10,054,941</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">8,523,018</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Less: Weighted-average shares of unvested common stock</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(16,698</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(16,698</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top" rowspan="2"> Total weighted-average shares used in computing net loss per share attributed to common stockholders</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr> <tr><td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">10,038,243</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">8,506,320</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Basic and diluted loss per share</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">(0.53</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">(0.99</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr></table> Potentially dilutive securities representing 2.1 million and 1.3 million weighted average shares of common stock were excluded for the years ended December 31, 2011 and 2010, respectively, because including them would have an anti-dilutive effect on net loss attributable to common stockholders per share. </div>

175000

111000

<div> (4) Financial Instruments Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). Inputs used to measure fair value are classified into the following hierarchy:   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> Level 1—Unadjusted quoted prices in active markets for identical assets or liabilities </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> Level 2—Unadjusted quoted prices in active markets for similar assets or liabilities; unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active; or inputs other than quoted prices that are observable for the asset or liability </td></tr></table>   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%"> <tr><td width="5%"> </td> <td valign="top" width="2%" align="left"></td> <td valign="top" width="1%"> </td> <td valign="top" align="left"> Level 3—Unobservable inputs for the asset or liability </td></tr></table> The Company's financial assets include $5.9 million at December 31, 2011 and $7.0 million at December 31, 2010, in money market funds, classified as cash equivalents, which are measured at fair value based on Level 1 inputs on a recurring basis. There were no transfers between any fair value hierarchy levels in 2011 or 2010. Fair Value of Other Financial Instruments The carrying amount of other financial instruments, including cash and accounts payable, approximated fair value due to their short maturities. As of December 31, 2011 and 2010, the Company did not have any debt outstanding. </div>

-83000

4000

-16000

6000000

125000

-65955000

-8420000

-5364000

<div> (13) Income Taxes Effective June 1, 2005, the Company changed from an S-Corporation to a C-Corporation. As an S-Corporation, the net operating loss carryforwards were distributed to the Company's stockholders; such amounts were not significant. Since June 2005 through December 31, 2011, for federal income tax purposes, the Company has net operating loss carryforwards of approximately $94.0 million, and approximately $687,000 of research and development credits that may be used to offset future taxable income. The net operating loss carryforwards will expire beginning 2025 through 2031. Utilization of net operating losses and tax credits, including those acquired as a result of the Merger, will be subject to an annual limitation due to ownership change limitations provided by IRC Section 382. The annual limitation may result in the expiration of the net operating losses and credits before utilization. As such, a portion of the Company's net operating loss carryforwards may be limited.   In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the period in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment. Due primarily to the Company's history of operating losses, management is unable to conclude that it is more likely than not that the Company will realize the benefits of these deductible differences, and accordingly has provided a valuation allowance against the entire net deferred tax asset of approximately $40.8 million at December 31, 2011, reflecting an increase of approximately $2.0 million from December 31, 2010. The deferred tax assets are primarily comprised of net operating loss carryforwards and research and experimentation credit carryforwards. As of December 31, 2011 the Company has not performed a Section 382 limitation study. Depending on the outcome of such a study, the gross amount of net operating losses recognizable in future tax periods could be limited. A limitation in the carryforwards would decrease the carrying amount of the gross amount of the net operating loss carryforwards, with a corresponding decrease in the valuation allowance recorded against these gross deferred tax assets. Income tax benefit attributable to our loss from operations before income taxes differs from the amounts computed by applying the U.S. federal statutory income tax rate of 35%, as a result of the following (in thousands):   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="76%" align="center"> <tr><td width="75%"> </td> <td valign="bottom" width="8%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="8%"> </td> <td> </td> <td> </td> <td> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom"> </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="6" align="center">Year ended December 31,</td> <td valign="bottom"> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom"> </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">      2011      </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">      2010      </td> <td valign="bottom"> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> U.S. federal income tax benefit at statutory rates</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(1,877</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">(2,947</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr><td valign="top"> State income tax benefit, net of federal benefit</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(161</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(253</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Research and experimentation credits</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(71</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(53</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr><td valign="top"> Settlement of liabilities assumed in the Merger</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(5,273</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Adjustment in tax basis of tangible and intangible assets acquired in the Merger</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(1,816</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr><td valign="top"> Other</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">152</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(54</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Change in valuation allowance</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">1,957</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">10,396</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr></table> Without regard to the deferred tax liability on the impaired IPR&D, the Company has had no provision for income taxes since inception due to its S-corporation status and its subsequent net operating losses.   Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting and the amounts used for income tax purposes, as well as operating loss and tax credit carryforwards. The income tax effects of temporary differences and carryforwards that give rise to significant portions of the Company's net deferred tax assets are as follows (in thousands):   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="92%" align="center"> <tr><td width="77%"> </td> <td valign="bottom" width="6%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="5%"> </td> <td> </td> <td> </td> <td> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">2011</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">2010</td> <td valign="bottom"> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Deferred tax assets:</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr> <tr><td valign="top"> Current deferred tax assets:</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Vacation accrual</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">21</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">30</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> Total current deferred tax assets</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">21</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">30</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Valuation allowance</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(21</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(30</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> Net current deferred tax assets</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Noncurrent deferred tax assets:</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr> <tr><td valign="top"> Net operating loss carryforwards</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">35,751</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">33,807</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Charitable contribution carryforwards</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">406</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">414</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Research and experimentation credits</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">687</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">616</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Capitalized intangibles</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">3,432</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">3,480</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Stock based compensation</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">399</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">374</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Depreciation and amortization</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">23</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Other</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">76</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">199</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Total noncurrent deferred tax assets</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">40,774</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">38,890</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Valuation allowance</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(40,774</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(38,890</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Net noncurrent deferred tax assets</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> Deferred tax liabilities:</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Current deferred tax liabilities:</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr> <tr><td valign="top"> Depreciation and amortization</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">(82</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Total noncurrent deferred tax liabilities</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(82</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> Valuation allowance</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">82</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Net deferred tax liabilities</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> Net noncurrent deferred tax assets</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">—  </td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr></table> Since the Company is in a loss carryforward position, the Company is generally subject to U.S. federal and state income tax examinations by tax authorities for all years for which a loss carryforward is available. Thus, the Company's open tax years extend back to 2005. The Company believes that its tax filing positions and deductions related to tax periods subject to examination will be sustained upon audit and does not anticipate any adjustment will result in a material adverse effect on the Company's financial condition, result of operations, or cash flow. For the years ended December 31, 2011 and 2010, the Company has no reserve for uncertain tax positions. The Company does not expect that the total amounts of unrecognized tax benefits will significantly increase or decrease within the subsequent twelve months. In the event the Company concludes it is subject to interest or penalties arising from uncertain tax positions, the Company will record interest and penalties as a component of other income and expense. No amounts of interest or penalties were recognized in the financial statements for the years ended December 31, 2011 and 2010. </div>

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<div> (10) Legal Matters On February 9, 2007, Nuvelo and certain of Nuvelo's former and then current officers and directors were named as defendants in a purported securities class action lawsuit filed in the United States District Court for the Southern District of New York. The suit alleged violations of the Securities Exchange Act of 1934 related to the clinical trial results of alfimeprase, which Nuvelo announced on December 11, 2006, and the suit sought damages on behalf of purchasers of Nuvelo's common stock during the period between January 5, 2006 and December 8, 2006. On December 29, 2010, ARCA and the other defendants reached a settlement of the litigation with the plaintiffs, after participating in mediation, and on February 25, 2011, the parties entered into a settlement agreement. ARCA's insurance carriers funded the settlement. On July 25, 2011 the order for final settlement became effective and the suit was dismissed. On or about December 6, 2001, Variagenics, Inc. was sued in a complaint filed in the United States District Court for the Southern District of New York naming it and certain of its officers and underwriters as defendants. The complaint purportedly was filed on behalf of persons purchasing Variagenics' stock between July 21, 2000 and December 6, 2000, and alleged violations of certain sections of the Securities Act of 1933, as amended, and the Securities Exchange Act of 1934, as amended. The complaint alleged that, in connection with Variagenics' July 21, 2000 initial public offering, or IPO, the defendants failed to disclose additional and excessive commissions purportedly solicited by and paid to the underwriter defendants in exchange for allocating shares of Variagenics' stock to preferred customers and alleged agreements among the underwriter defendants and preferred customers tying the allocation of IPO shares to agreements to make additional aftermarket purchases at predetermined prices. ARCA was involved in this litigation as a result of Nuvelo's merger with Variagenics in January 2003. On April 1, 2009 the parties entered into a settlement agreement. On October 5, 2009, the Court approved the settlement agreement. ARCA's share of the settlement was approximately $385,000 and was funded by ARCA's insurance carrier. Although the settlement was approved by the Court, it had been appealed by members of the class. On January 9, 2012 the appeal was dismissed by the Court and the suit was settled. </div>

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<div> (12) Employee Benefit Plans The Company has a 401(k) plan and makes a matching contribution equal to 100% of the employee's first 3% of the employee's contributions and 50% of the employee's next 2% of contributions. The Company adopted the plan in 2006 and contributed $80,000 and $109,000 for the years ended December 31, 2011 and 2010, respectively, and has contributed $583,000 from Inception through December 31, 2011. </div>

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<div> (5) Property and Equipment Property and equipment consist of the following (in thousands):   <table style="border-collapse: collapse;" border="0" cellspacing="0" cellpadding="0" width="100%" align="center"> <tr><td width="42%"> </td> <td valign="bottom" width="7%"> </td> <td> </td> <td valign="bottom" width="7%"> </td> <td> </td> <td> </td> <td> </td> <td valign="bottom" width="7%"> </td> <td> </td> <td> </td> <td> </td></tr> <tr><td valign="bottom"> </td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" align="center">Estimated Life</td> <td valign="bottom">  </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">December 31, 2011</td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td style="border-bottom: #000000 1px solid;" valign="bottom" colspan="2" align="center">December 31, 2010</td> <td valign="bottom"> </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Computer equipment</td> <td valign="bottom">  </td> <td valign="bottom" align="center">3 years</td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">104</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">206</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Lab equipment</td> <td valign="bottom">  </td> <td valign="bottom" align="center">5 years</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">142</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">142</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Furniture and fixtures</td> <td valign="bottom">  </td> <td valign="bottom" align="center">5 years</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">93</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">398</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr><td valign="top"> Computer software</td> <td valign="bottom">  </td> <td valign="bottom" align="center">3 years</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">176</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">176</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top"> Leasehold improvements</td> <td valign="bottom">  </td> <td valign="bottom" align="center">Lesser of useful life or life of the lease</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">18</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">744</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">533</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">1,666</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr bgcolor="#cceeff"><td valign="top" colspan="3"> Less accumulated depreciation and amortization</td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(467</td> <td valign="bottom" nowrap="nowrap">) </td> <td valign="bottom"> </td> <td valign="bottom"> </td> <td valign="bottom" align="right">(976</td> <td valign="bottom" nowrap="nowrap">) </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr> <tr><td valign="top"> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">$</td> <td valign="bottom" align="right">66</td> <td valign="bottom" nowrap="nowrap">  </td> <td valign="bottom"> </td> <td valign="bottom">$</td> <td valign="bottom" align="right">690</td> <td valign="bottom" nowrap="nowrap">  </td></tr> <tr style="font-size: 1px;"><td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td> <td valign="bottom"> </td> <td valign="bottom">  </td> <td valign="bottom">  </td> <td> </td></tr></table> For the years ended December 31, 2011 and 2010, and for the period from Inception through December 31, 2011, depreciation and amortization expense was $602,000, $338,000 and $1.7 million, respectively. </div>

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<div> (6) Related Party Arrangements Transactions with the Company's President and Chief Executive Officer Effective July 1, 2011, the Company entered into an unrestricted research grant with its President and Chief Executive Officer's research laboratory, or the Lab, for $160,000 for a one-year term for the advancement of research in cardiovascular disease. For the period from July 1, 2010 through June 30, 2011, the Company provided funding to the Lab under another unrestricted research grant for $226,000. In the first half of 2011, the Company provided research funding for the lab of approximately $92,000, in accordance with a similar unrestricted research grant arrangement. Funding of the unrestricted research grants is contingent upon the Company's financial condition, and can be deferred or terminated at the Company's discretion. Total expense under these arrangements for the years ended December 31, 2011 and 2010 was $155,000 and $255,000, respectively, and $1.4 million from Inception through December 31, 2011. The Company was a party to a materials transfer agreement with the University of Colorado, under which the Company paid $35,000 per year to maintain the Heart Tissue Bank associated with the President and Chief Executive Officer's research lab at the University of Colorado. Total expense for the year ended December 31, 2011 was $26,000 and was $227,000 from Inception through December 31, 2011. </div>

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<div> (9) Equity Distribution Agreement In 2009 the Company entered into an equity distribution agreement, or the Agreement, with Wedbush Securities Inc., the Agent, under which the Company could, from time to time, offer and sell its common stock through the Agent. On April 30, 2010, the Company amended the Agreement to permit it to sell up to an aggregate of $20 million in shares, which were registered on a registration statement on Form S-3 (File No. 333-148288). In the year ended December 31, 2010, the Company sold 1,164,600 shares of common stock under this Agreement and realized $7.2 million of proceeds, net of $338,000 of offering costs. On May 23, 2011 the Company terminated this agreement. No shares of common stock were sold during 2011 under this agreement. </div>

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