12. Income Taxes

The Company recorded a provision for income taxes of $0.2 million and $0.1 million, for the years ended December 31, 2011 and 2010, respectively, and a benefit for income taxes of $0.4 million for the year ended December 31, 2009. The provision in 2011 primarily consisted of state and foreign income taxes and foreign deferred tax benefits. The benefit in 2009 consisted of an "accelerated research credit" of $0.4 million, partially offset by state income taxes.

The significant components of the Company's deferred tax assets and liabilities are as follows (in thousands):


	December 31,
	2011			2010
Deferred tax assets:
Net operating loss carryovers	$	182,674		$	145,090
Tax credit carryforwards		19,076			14,714
Depreciation and amortization		3,619			1,174
Accruals and reserves		14,057			7,169
Deferred revenue		8,804			6,789
Stock-based compensation		4,734			4,397
Other		118			30

Gross deferred tax assets		233,082			179,363
Valuation allowance		(202,004	)		(179,162	)

Net deferred tax assets		31,078			201
Deferred tax liabilities:
Intangible assets		(30,960	)		(201	)

Net deferred tax assets reflected in balance sheet	$	118		$	—

Management reviews the recognition of deferred tax assets to determine if realization of such assets is more likely than not. The realization of the Company's deferred tax assets is dependent upon future earnings. The Company has been in a cumulative loss position since inception which represents a significant piece of negative evidence. Using the more likely than not criteria specified in the applicable accounting guidance, this negative evidence cannot be overcome by positive evidence currently available to the Company and as a result the Company has established a full valuation allowance against its deferred tax assets. The Company's valuation allowance increased by $22.8 million and $1.5 million in the years ended December 31, 2011 and 2010, respectively. The valuation allowance in both 2011 and 2010 includes $0.1 million related to excess tax benefits of stock option deductions prior to the adoption of ASC Topic 718. The benefits will increase additional paid-in capital when realized.

Since inception, the Company has incurred operating losses and, accordingly, has not recorded a provision for federal income taxes for any periods presented. As of December 31, 2011, the Company had U.S. federal and state net operating losses of $560.2 million and $326.5 million. The U.S. federal net operating loss carryforwards will expire at various dates beginning in 2012 and through 2031 if not utilized. The state net operating loss carryforwards will expire at various dates beginning from 2012 and through 2031, if not utilized. In addition, as of December 31, 2011 and 2010, the Company had $35.3 million and $13.3 million in federal deductions, respectively, and $32.4 million and $11.8 million, respectively, in state deductions related to excess tax benefits from stock options which are not included in the net operating loss carryforward amounts in the table above since they have not met the realization criteria of ASC Topic 718. The tax benefits from these deductions will increase additional paid-in capital when realized. Additionally, the Company has U.S. federal, California and other U.S. states research and development credits of $15.6 million, $18.7 million and $1.7 million as of December 31, 2011, respectively. The U.S. federal research and development credits will begin to expire in 2020 and through 2031, and the California research and development credits have no expiration date. The credits related to other various U.S. states will begin to expire in 2015 and through 2026. During the year ended December 31, 2010, the Company performed a Section 382 study of the Internal Revenue Code (and similar state provisions), and a research and development credit study, and adjusted its deferred tax assets related to its net operating loss carryforwards and its research and development credits accordingly.

On January 1, 2009, the Company adopted the guidance related to accounting for uncertainty in income taxes (ASC Topic 740-10). This topic prescribes a recognition threshold and measurement attribute to the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The guidance also provides guidance on derecognition, classification, accounting in interim periods and disclosure requirements for uncertain tax positions. The standard requires the Company to recognize the financial statement effects of an uncertain tax position when it is more likely than not that such position will be sustained upon audit. The Company's adoption of ASC Topic 740-10 did not result in a cumulative effect adjustment to accumulated deficit. Upon adoption the Company recorded a cumulative unrecognized tax benefit of $9.3 million, which was netted against deferred tax assets with a full valuation allowance. In the event that any unrecognized tax benefits are recognized, the effective tax rate will not be affected. The Company will recognize accrued interest and penalties related to unrecognized tax benefits as interest expense and income tax expense, respectively, in statements of operations.

The following table reconciles the Company's unrecognized tax benefits for the years ended December 31, 2011 and 2010 (in thousands):


	December 31,
	2011			2010
Balance as of January 1	$	7,801		$	6,970
Reductions of tax positions related to prior year		(86	)		—
Additions for tax positions related to prior year		—			22
Additions for tax positions related to current year		663			809
Additions for tax positions related to acquisition		4,165			—

Balance as of December 31	$	12,543		$	7,801

The total amount of unrecognized tax benefits that would affect the Company's effective tax rate is $115 thousand and $36 thousand as of December 31, 2011 and 2010, respectively. The liability for uncertain income taxes as of December 31, 2011 includes interest and penalty of $7 thousand.

The Company's only major jurisdictions are the United States, various state jurisdictions and China. The tax years 2000 through 2011 remain open and subject to examination by the appropriate governmental agencies in the U.S. due to tax carry forward attributes.