Thrombin-mediated aggregation of ruby-eye platelets. Wild-type (A) and ruby-eye (B) platelets were incubated with the indicated concentrations of thrombin and percentage of light transmission was recorded. (C) Mean percentage aggregation in wild-type and ruby-eye platelets was plotted as a function of thrombin concentration with standard deviation indicated (n = 3-8 aggregations/condition, n = 5 mice). (D) Ruby-eye platelets were incubated with 2 μM ADP alone, 25 mU/mL thrombin alone, or 25 mU/mL thrombin plus 2 μM ADP as indicated. Platelet aggregation was measured with constant stirring.