Income Taxes

6 Months Ended

Jun. 30, 2012

Income Taxes [Abstract]

Income Taxes

8. INCOME TAXES

At December 31, 2011, the Company had net deferred tax assets of approximately $116.8 million. The net deferred tax assets are primarily composed of U.S. federal and state tax net operating loss carryforwards, U.S. federal and state research and development credit carryforwards and share-based compensation expense. Due to uncertainties surrounding the Company’s ability to generate future taxable income to realize these assets, a full valuation allowance has been established to offset its net deferred tax asset. Additionally, the Internal Revenue Code rules could limit the future use of its net operating loss and research and development credit carryforwards to offset future taxable income based on ownership changes and the value of the Company’s stock.