After an enthusiastic midweek hop, biotech stocks rounded out a blasé end-of-week performance with business updates and legal matters Friday.

Celera ( CRA), however, emerged as a winner. The company said Friday it received a $2 million milestone payment from Merck ( MRK) for the advancement of odanacatib for osteoperosis into a phase III clinical trial.

Celera, an Applera ( ABI) subsidiary, and Merck have had a collaboration agreement since 1996 on a program targeting cathepsin K, an enzyme believed to play a role in osteoperosis. Merck has been sole responsible for research and development since February 2003.

Celera shares gained 3.7% to $14.05. Applera was unchanged. Merck was 1.2% lower at $51.65.

Other stocks dealt with the aftermath of business updates:

Idenix Pharmaceuticals ( IDIX) lost ground after announcing a restructuring plan to focus on hepatitis C virus (HCV) and HIV programs. The company amended an agreement with Novartis ( NVS) to discontinue all activities for hepatitis B treatment Tyzeka and cutting a third of its workforce. The plan is expected to result in annual savings of $40 million to $45 million.

Idenix, a component of the Nasdaq biotechnology index, lost 17 cents, or 5.6%, to $2.86. The index was down 5.03, or 0.6%, to 854.37.

Also on the way down was Par Pharmaceuticals ( PRX), which said it expects lower earnings as competitive pressures have resulted in scaled back sales of several products. It gave guidance of between 95 cents a share and $1.10 a share -- or between $1.05 and $1.20 a share after one-time events -- on revenue of $730 million to $765 million. The Thomson Financial consensus target was $1.56 a share.

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