Integrin α2β1–induced PI3Kβ activation is impaired in Pyk2-deficient platelets. Comparative analysis of Akt phosphorylation in wild-type and Pyk2-knockout platelets on adhesion to monomeric collagen for 10, 30, and 60 minutes. A representative immunoblot is shown in panel A. Quantification of Akt phosphorylation, performed by densitometric analysis of the immunoreactive bands, is shown in panel B. Black bars are wild-type platelets, gray bars are Pyk2-knockout platelets. Data are the means ± SD of 3 different experiments. *P < .05.