Effect of thrombin, HLE, and Cat G on the expression of the thrombin receptor at the surface of ECs. IVECs in suspension were incubated for 5 minutes with thrombin (A and B), HLE (C), or Cat G (D) at the indicated concentrations and were then reacted with the murine antithrombin receptor MoAb IIaR-A, followed by FITC-conjugated antimouse IgG, as detailed in Materials and Methods. For each experimental condition, the observed tracing (in black) is shown for comparison with a typical tracing (superimposed) representative of the control condition (ie, without pretreatment with any of the proteinases). The MFI value for the control irrelevant monoclonal IgG was 10.7 ± 1.1 (n = 3). Tracings are representative of four distinct experiments.