Dok-2 tyrosine phosphorylation induced by activation of thrombin and collagen receptors. Role of outside-in signaling via the integrin α_IIbβ₃. Phosphotyrosine immunoprecipitated proteins from human (A) or murine (B) platelets were separated by SDS-PAGE and immunoblotted using anti–Dok-2 antibodies. Platelets were activated with thrombin (1.0 U/mL, 90 seconds), convulxin (3 μg/mL, 2 minutes), and collagen (10 μg/mL, 2.5 minutes). (A) Platelets were activated in the presence or absence of the α_IIbβ₃ antagonist lotrafiban (10 μM). (B) Wt indicates wild-type mice; –/–, αIIb-deficient mice; IP, immunoprecipitation; and IB, immunoblot. Images represent at least 3 independent experiments.