Concentration-response curves of Y-27632 effect on platelet shape change induced by different agonists. Samples were preincubated with the given concentrations of inhibitor for 30 minutes at 37°C. Values are the percent maximum induced by the agonist in the absence of Y-27632. (a) ADP (2 μmol/L; ○) and ionomycin (100 nmol/L; ◊). (b) YFLLRNP (300 μmol/L; ○) and U46619 (100 nmol/L; ◊). Data are mean ± SE of 4 to 6 independent experiments.