Platelet-derived COMP involvement in hemostasis and thrombosis. (A) Representative platelet aggregation tracings following different thrombin treatments: 0.1 U/mL (top) or 0.02 U/mL for 1 hour plus an additional 0.08 U/mL thrombin (bottom). Bar graph shows statistical results of aggregation maximal percentages from 4 independent results. *P < .05; NS, not significant. (B-D) Tail-bleeding time (B), blood clotting time (C), and carotid artery occlusion time (D) in COMP^−/− mice with platelet transfusion. n = 6, *P < .05.