Time course of Shc tyrosine phosphorylation induced by botrocetin-vWF. Platelets were activated with 3 μg/mL of botrocetin and 10 μg/mL of vWF, and reactions were terminated by adding lysis buffer after the indicated time intervals. Shc was immunoprecipitated with anti-Shc polyclonal Ab. The sample was then Western-blotted using the antiphosphotyrosine MoAb, 4G10. The data are representative of three experiments.