Effect of deficiency of SLP-76 or FcRγ on platelet procoagulant activity.

(A) Prothrombinase activity was measured with SLP-76^+/−(open bars; n = 5), SLP-76^−/− (filled bars; n = 4), or FcRγ^−/− (hatched bars; n = 4) platelets that were stimulated with collagen (40 μg/mL), convulxin (250 ng/mL), or ionomycin (3 μM). (B) Prothrombinase activity was measured with SLP-76^+/− (open bars; n = 10) or SLP-76^−/−(filled bars; n = 10) platelets that were stimulated with thrombin (0.5 U/mL), collagen (40 μg/mL), or thrombin plus collagen. Values are expressed as percent of unstimulated control platelets. *P < .05 versus unstimulated platelets. †P < .05 versus SLP-76^+/− platelets stimulated with collagen.