Actin polymerization inhibitors have no effect on VWF-induced TXB2 production but enhance platelet aggregation response to VWF. Human platelets, preincubated with the indicated doses of cytochalasin D or latrunculin A, were stimulated with 10 µg/mL VWF with or without 0.35 mg/mL ristocetin or unstimulated at 37°C for 6 minutes in the aggregometer. (A) Samples were analyzed for TXB₂ and (B) aggregation traces were recorded.