ADP receptor blockers attenuate TCIPA but potentiate TCIPS, whereas inhibition of αIIbβ3 affects both. (A,C) Bar graph comparing the effect of the indicated inhibitors on platelet aggregation (n = 3/6; **P < .01) and dense-granule secretion (n = 5/6; *P < .05) elicited by PC3M-luc. CD41/SZ22 antibody (Beckman Coulter, UK), was tested in platelet secretion but not aggregation. Results are expressed and normalized for each donor as explained in the Figure 3 legend (data are expressed as mean ± SEM). (B) Representative aggregation trace showing the effect of the reported inhibitors on TCIPA elicited by PC3M-luc (100 × 10³ cells per mL). (D) β₃ integrin is phosphorylated following platelet stimulation with PC3M. Lysates from resting platelets or platelets (300 × 10³ platelets per μL) activated with either TRAP (10μM) or PC3M cells (100 × 10³  cells per mL) were immune-blotted with a phospho-specific integrin β₃ antibody (pY759) as indicated. Loading protein levels were determined after stripping and reprobing of the same gels using a pan-β₃ antibody. (Left panel) The band intensities are estimated by densitometry, (right panel) adjusted for differences in loading levels as detected by pan β₃. Data are expressed as AU and represent mean ± SEM for 4 independent experiments. AU, arbitrary unit; NT, not tested.