Analysis of cPLA₂, ERK, and p38 MAPK phosphorylation. (A) Washed platelets from WT and Pyk2-KO mice were stimulated with 0.05 U/mL of thrombin for 0, 5, or 15 minutes as indicated. The phosphorylation of cPLA₂ was evaluated by immunoblotting with a phosphospecific Ab, followed by a subsequent immunoblotting with anti cPLA₂, as indicated on the right. Quantification of cPLA₂ phosphorylation was performed by densitometric analysis of the immunoblots. Data are reported in the histogram as means ± SD of 4 different experiments. ***P < .001. (B-C) Phosphorylation of ERK (B) and p38 MAPK (C) in platelets from WT and Pyk2-KO mice (Pyk2-KO) stimulated with 0.05 U/mL of thrombin for 0.5, 1, and 2 minutes was analyzed by immunoblotting with phosphospecific Abs as indicated on the right. Blotting with anti-p38 MAPK or anti-ERK was performed as a control for equal loading. Quantitative evaluation of protein phosphorylation is reported in the histograms as the means ± SD of 3 different experiments. *P < .05; **P < .01