Effect of u-PA enrichment of platelets on thrombin-stimulated plasminogen activation. Platelets were isolated from PRP without (circles) or with a 30-minute preincubation with either 1 μg/mL of scu-PA (triangles) or thromb-UK (squares) and incubated with plasminogen and S2403 in the absence (open symbols) or presence (closed symbols) of 5 U/mL thrombin. Mean ± standard deviation (SD) of three experiments.