TSSC6^–/– platelets display normal soluble FITC-fibrinogen binding, JON/A mAb binding, and alpha granule release following treatment with thrombin, PAR-4 peptide, ADP, and ADP in synergy with epinephrine. (A) FACS analysis of FITC-conjugated fibrinogen binding to platelets stimulated with thrombin (1 U/mL), PAR-4 (250 μM), PMA (20 μM), ADP (10 μM), ADP (10 μM) + epinephrine (20 μM), or unstimulated (control). Results are cumulative data from 3 independent assays and are presented as MFI ± SEM. (B) Flow cytometric analysis of JON/A-PE mAb binding to platelets stimulated with 0.5 to 1.0 U/mL thrombin, 125 to 250 μM PAR-4, 10 to 20 μM ADP, 10 to 20 μM ADP + 20 μM epinephrine, 2.5 to 5 μg/mL CRP, or unstimulated (control). Results are cumulative data from 3 independent experiments and are presented as MFI ± SEM. (C) Surface expression of P-selectin was determined for washed platelets stimulated by 0.5 to 5 U/mL thrombin or 100 to 400 μM PAR-4 agonist peptide and then stained with either a buffer control and FITC–P-selectin mAb for wild-type and TSSC6^–/– platelets. FITC-labeled samples were analyzed on a FACS Calibur analysis. Results are cumulative data from 3 independent experiments and are presented as MFI ± SEM.