FcγRIIa, Syk, and PKC activation is necessary for PC3M to induce platelet aggregation and secretion. (A-B) Representative aggregation trace showing the effect of the reported inhibitors on PC3M-luc (100 × 10³ cells per mL)–induced platelet aggregation. (C, E, F) Bar graph comparing the effect of the indicated inhibitors on platelet aggregation and dense-granule secretion (n = 4/9; *P < .05; **P < .01; ***P < .0001) elicited by PC3M-luc. Results are expressed and normalized for each donor as explained in the Figure 3 legend (data are expressed as mean ± SEM). (D) PC3M cells do not induce mouse platelet secretion. Mouse WPs (300 × 10³ platelets per μL) were stimulated with PC3M cells (100 × 10³ cells per mL) and results for luminescence, expressed as AAU, derived from platelet ATP/ADP release are shown. CRP (1 μg/mL)–stimulated platelets were used as the positive control (data are expressed as mean ± SEM).