Fig. 5.

APC desensitizes PAR₁ to thrombin signaling. (A) EA.hy926 cells were preincubated with or without 10 nM APC for 1 hour at 37 °C and then stimulated with thrombin (Th) or APC at 37 °C; ERK1/2 activation was examined by immunoblotting. Data (mean ± SE) are expressed as the fold-increase over untreated control and are the averages of three separate experiments. The difference between thrombin-induced ERK1/2 activation in untreated versus APC-pretreated cells was significant (* P < 0.05). (B) Control and caveolin-1 (CAV1)–deficient cells were preincubated with 10 nM APC for 1 hour at 37 °C and then stimulated with or without 10 nM thrombin (Th) at 37 °C, and ERK1/2 activation was determined. (C) Cells were pretreated with or without 10 nM APC for 1 hour at 37 °C and then stimulated with or without 10 nM thrombin (Th) at 37 °C, and activated RhoA was examined. Similar findings were observed in two independent experiments.