Thrombin-induced platelet functional responses are inhibited by Shh antagonists. Binding of Alexa fluor 488-fibrinogen (A-B) and FITC-labeled PAC-1 (C-D) to platelets treated with different reagents (thrombin, 0.1 U/mL for fibrinogen binding and 0.25 U/mL for PAC-1 binding; cyclopamine, 10 μM; and vismodegib, 25 μM) as indicated. (E-F) P-selectin externalization in platelets induced by 0.25 U/mL thrombin in the presence of vehicle, cyclopamine (10 μM), or vismodegib (25 μM), as indicated. (G-H) EV release from platelets pretreated with vehicle, cyclopamine, or vismodegib upon stimulation with thrombin (0.5 U/mL) as indicated. Figures are representative of ≥5 individual experiments (mean ± standard error of the mean). *P < .05 as compared with resting platelets and #P < .05 as compared with thrombin-stimulated platelets.