Exhibit 12.1

Statement of Computation of Ratios

	Year Ended December 31,															Nine Months Ended September 30, 2012
	2007			2008			2009			2010			2011
	(in thousands)
Earnings:
Net loss before income taxes	$	(27,680	)	$	(45,570	)	$	(45,889	)	$	(73,554	)	$	(83,912	)	$	(46,738	)
Add: Fixed charges		426			1,816			9,305			10,179			7,776			8,829
Earnings as defined	$	(27,254	)	$	(43,754	)	$	(36,584	)	$	(63,375	)	$	(76,136	)	$	(37,909	)
Fixed Charges:
Interest expensed		377			1,718			9,188			10,013			7,644			8,730
Estimated interest component of rent expenses		49			98			117			166			132			99
Total fixed charges		426			1,816			9,305			10,179			7,776			8,829
Ratio of earnings to fixed charges(1)		—			—			—			—			—			—

(1) Earnings were insufficient to cover fixed charges by approximately $27.7 million, $45.6 million, $45.9 million, $73.6 million, $83.9 and $46.7 million for the years ended December 31, 2007, 2008, 2009, 2010, 2011 and for the nine months ended September 30, 2012, respectively. The ratio of earnings to fixed charges was less than one-to-one for each of the periods presented. We have not included a ratio of earnings to combined fixed charges and preferred stock dividends because we do not have any preferred stock outstanding as of the date of this prospectus.