Akt phosphorylation is decreased in Lyn-deficient platelets relative to wild-type platelets in response to thrombin and the PAR4 peptide.

Lyn-deficient platelets diminished Akt phosphorylation in response to γ-thrombin, α-thrombin, or PAR4 peptide concentrations that produce secretion-dependent aggregation (A). However, high concentrations of γ-thrombin, α-thrombin, or PAR4 peptide induced Akt phosphorylation in Lyn-deficient platelets. Immunodetection of actin was performed to show that a similar amount of protein was present in each lane. As a control, increasing concentrations of U46619 were used to activate Lyn-deficient and wild-type platelets (B). Akt phosphorylation by Lyn-deficient platelets was normal in response to U46619, so the diminished Akt phosphorylation was specific to thrombin receptor signaling.