Tfpi^−/−:Par4^−/− mice have enhanced thrombin generation in vivo and in vitro. (A) TAT complex in plasma is elevated in Tfpi^−/−:Par4^−/− mice compared with Par4^−/− mice (13.4 ± 18.1 ng/mL, n = 20 vs 6.7 ± 13.0 ng/mL, n = 12; mean ± standard deviation; P = .014). (B) Real-time thrombin generation in PPP from wild-type, Par4^−/−, and Tfpi^−/−:Par4^−/− mice was assessed by calibrated automated thrombography. Lines represent the mean thrombin generated in pooled samples (n = 2 for each genotype) from 3 separate experiments using a total of 6 mice for each genotype.