Effect of HS1 deficiency on ex vivo platelet functional responses. (A,B) Washed platelets from wild-type (WT) and HS1-null (KO) mice were stimulated with different concentrations of convulxin (A) or AYPGKF (B), and their aggregations were measured and compared. (C,D) Washed platelets from wild-type and HS1-null mouse platelets were stimulated with different concentrations of convulxin (C) or AYPGKF (D) and labeled with the JON/A αIIbβ3 activation-dependent antibody. Binding of the antibody was measured by flow cytometry and graphed (normalized to maximal stimulation). Wild-type mouse platelets are indicated by the solid line, and the HS1-null mouse platelets are indicated by the dashed line. A 2-way ANOVA was used to calculate the statistical significance for the difference in the dose-response curve (P< .05). Error bars indicate standard error. (E,F) Washed platelets from wild-type and HS1-null mice were stimulated with different concentrations of convulxin (E) and AYPGKF (F), and their dense-granule secretion was measured. The data are representative of at least 3 different experiments.