FIG. 4.

PKC is not involved in α-thrombin-induced Ral activation. (A) PKC activation does not lead to rapid Ral activation. Platelets were stimulated with PMA (10 nM) for 1 and 3 min. (B) Inhibition of PKC does not block α-thrombin-induced Ral activation. Platelets were treated with the PKC inhibitor bisindolylmaleimide (B, 5 μM, 1 min) or the kinase inhibitor staurosporine (S, 1 μM, 5 min) prior to stimulation with 0.1 U of α-thrombin (α-thr) per ml for 1 min or were stimulated with α-thrombin alone. Ral activation was analyzed as described in the legend to Fig. 2. ––, resting platelets. ctrl, control.