Survival of PAR-deficient mice after endotoxin challenge: double knockouts. (A) Par1^–/–:Par2^–/– (50% C57BL/6, 50% 129SVJae) mice and strain-, age-, and sex-matched controls were injected intraperitoneally with LPS and survival monitored as indicated. (B) Par2^–/– (about 97.5% C57BL/6, about 2.5% 129SVJae) females and littermate controls were injected intraperitoneally with hirudin (1 mg/kg) 30 minutes before and 30 minutes, 2 hours, and 4 hours after intraperitoneal injection of low-dose LPS.