Fig. 1.

Thrombin and APC concentration dependence of PAR-1 cleavage on endothelial cells transfected with the PAR-1 cleavage reporter construct. (A) PAR-1 cleavage by various concentrations of either thrombin (■) or APC in the absence (○) and presence (●) of a saturating concentration of sEPCR (500 nM) was monitored by an alkaline phosphatase assay as described in Materials and Methods. (B) The same as in A except that Gla-domainless APC was used in the cleavage reaction. The activities with APC are normalized to percentage maximal activity observed with 10 nM thrombin (Th).