Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2014

Revenue Accounted for 10% or More of Total Revenues

Customers whose collaborative research and development revenue accounted for 10% or more of total revenues were as follows:

	Three Months Ended March 31,
	2014			2013
Bristol-Myers Squibb Company and Pfizer Inc.		19	%		64	%
Bayer Pharma, AG and Janssen Pharmaceuticals, Inc.		38	%		36	%
Daiichi Sankyo, Inc		40	%		—