Effect of APC on thrombin generation on endothelial cells.

Endothelial cells were preincubated with the indicated concentration of APC and 150 nM protein S. To initiate thrombin generation, plasma concentrations of prothrombin, factor X, and factor V, with factor VIIa but without any coagulation inhibitors, were added to the cells. The plot shows the amount of thrombin as a function of time.