Phosphorylation of ephrinB1 and EphA4 in platelets. (A) Platelets were incubated with GST-EphB1 (5 μg/mL), GST-ΔEphB1 (5 μg/mL), or monomeric His-EphB1 (10 μg/mL) for 30 minutes and then lysed. EphrinB1 was immunoprecipitated (IP) and then immunoblotted (IB) with the antiphosphotyrosine antibodies PY20 and 4G10. Afterward, the blots were reprobed with anti-ephrinB1. The results shown are representative of 2 experiments. (B) Platelets were incubated with GST-EphB1 (5 μg/mL) for the times indicated. EphrinB1 was immunoprecipitated and then immunoblotted as indicated. (C) Platelets were incubated with GST-ephrinA4 for the times indicated and then lysed. EphA4 was immunoprecipitated and then immunoblotted as indicated. The results are representative of 3 experiments.