Pretreatment with PBX3 siRNA protected mice against lethal endotoxemia and inhibited the release of TNF-α and HMGB1. (A) Mice (n=15 per group) were injected with PBX3 siRNA, followed 30 min later by a lethal infusion of endotoxin (LPS; 5 mg/kg intraperitoneal) and followed with PBX3 siRNA injection every three days. The Kaplan-Meyer method was used to compare the differences in survival rates between groups. In parallel, serum levels of (B) TNF-α at 1–4 h and (C) HMGB1 at 24 h were measured by ELISA (n=6 mice per group). (D) Mice (n=15 per group) were injected with endotoxin (LPS, 5 mg/kg), followed 30 min later by PBX3 siRNA injection every three days. The Kaplan-Meyer method was used to compare the differences in survival rates between groups. (E) Serum level of HMGB1 at 32 h was measured by ELISA (n=6 mice per group). Values are presented as the mean + standard deviation (n=3). **P<0.01 vs. LPS + saline for (A), **P<0.01 vs. LPS + PBX siRNA for (D), **P<0.01 vs. saline or as indicated. PBX3, pre-B cell leukemia transcription factor 3; HMGB1, high mobility group box 1; LPS, lipopolysaccharide; siRNA, small interfering RNA; TNF-α, tumor necrosis factor-α.