Flow cytometric analyses of resting and A23187-treated platelets. Resting (A) or A23187-treated (B) platelets were immunostained with α–TF-5. A23187-treated platelets were also treated with an anti–P-selectin antibody (C). The positive analysis regions (horizontal bars) were defined such that less than 99% of the cells stained with an irrelevant isotype-matched mouse IgG were positive. The percentage of positive cells in each of these analysis regions is shown.