Effect of total fibrinogen on the ETP-based APC response in pooled normal plasma and in FV Leiden heterozygous plasma. Thrombin generation was initiated in defibrinated and whole normal plasma (A-B) with 10 pM TF in the presence of 0-5 nM APC and the residual ETP (ETP_+APC/ETP_−APC) was plotted as a function of the APC concentration (C). Thrombin generation was initiated in defibrinated and whole FV Leiden heterozygous plasma (D-E) with 10 pM TF in the presence of 0-10 nM APC and the residual ETP was plotted as a function of the APC concentration (F). Averages of triplicate experiments are shown. Error bars indicate the standard error of the mean.