Enhanced aggregation of Cdc42^−/− platelets at low agonist concentrations. (A-C) Aggregometry studies. prp from wild-type (■) or Cdc42^−/− (▩) mice was stimulated with the indicated agonists; light transmission was recorded on a Fibrintimer 4 channel aggregometer. Thrombin measurements were performed using washed platelets. The results are representative of 3 individual experiments. (A-B) Representative aggregation curves. (C) Bar graphs of results obtained by aggregometry. Results are given as the mean percentage of aggregation ± SD. P values from left to right: **.002; *.032; ***< .001.