The permeability barrier-enhancing effect of thrombin is reversed by the ligand occupancy of EPCR with PC-S195A, but not with factor VIIa. EA.hy926 cells were incubated with APC (10 nmol/L) and thrombin (2 nmol/L) in the absence and presence of either PC-S195A or factor VIIa (50 nmol/L) for 3 hours before inducing permeability with 5 nmol/L thrombin for 10 minutes. B-αEPCR is blocking anti-EPCR (clone RCR-252), B-αPAR-1 (H-111) is blocking anti-PAR-1, and NB-αPAR-1 (S-19) is nonblocking anti-PAR-1, which have been incubated with endothelial cells for 30 minutes before treatment with APC. Baseline represents the permeability of untreated control cells not stimulated with thrombin. Error bars represent SD.