Quarters Ended

March 31,

June 30,

September 30,

December 31,

2012:

Collaboration revenue

$

36,825

$

42,912

$

64,798

$

37,161

Operating expenses

$

(35,717

)

$

(43,887

)

$

(64,390

)

$

(63,916

)

Income (loss) from operations

$

1,108

$

(975

)

$

408

$

(26,755

)

Net income (loss)

$

440

$

(5,500

)

$

(4,537

)

$

(31,660

)

Basic net income (loss) per common share

$

0.01

$

(0.08

)

$

(0.06

)

$

(0.43

)

Diluted net income (loss) per common share

$

0.01

$

(0.08

)

$

(0.06

)

$

(0.43

)

Weighted-average common shares used in the calculation of basic net income (loss) per common share

71,907

72,770

73,697

74,489

Weighted-average common shares used in the calculation of diluted net income (loss) per common share

77,299

72,770

73,697

74,489

2011:

Collaboration revenue

$

14,709

$

15,799

$

14,940

$

14,941

Operating expenses

$

(23,774

)

$

(26,175

)

$

(26,430

)

$

(26,940

)

Loss from operations

$

(9,065

)

$

(10,376

)

$

(11,490

)

$

(11,999

)

Net loss

$

(8,452

)

$

(9,474

)

$

(10,044

)

$

(10,871

)

Basic and diluted net loss per common share

$

(0.12

)

$

(0.14

)

$

(0.14

)

$

(0.15

)

Weighted-average common shares used in the calculation of basic and diluted net loss per common share

69,325

69,776

69,818

70,749