Thrombin binding to L2H cells transiently expressing GP V. L2H cells were either sham-transfected with an empty plasmid or transfected with a plasmid containing the gene for GP V. Seventy-two hours after transfection, the thrombin-binding capacity of the cells was compared as in Fig 1. *Binding to this cell line was significantly greater than to the other 2 cell lines (Student's t test: n = 5, t = 13.263, P < .001).