Increased integrin activation and α-granule exocytosis in platelets from RGS10^−/−mice. Platelets from RGS10^−/− and littermate control mice (WT) were stained with fluorophore-conjugated antibodies to P-selectin or activated α_IIbβ₃ (Jon/A antibody) after incubation with a PAR4 agonist peptide (AYPGKF) (A), a TxA₂ mimetic (U46619) (B), or ADP (C) at the concentrations indicated (N = 7). N.S., not significant.