P-selectin exposure, annexin V binding, and coated platelet formation in FXIIIA^-/- platelets. Platelets isolated from FXIIIA^+/- (n = 5) (▪) or FXIIIA^-/- (n = 7) (▦) mice were stimulated with the indicated agonists for 7 minutes. The percentage of platelets with P-selectin surface expression (A) and annexin V binding (B) was measured by flow cytometry. (C) The percentage of coated platelets, defined as high fibrinogen, low PE-JON/A binding, was determined by 2-color flow cytometry.