A20 deficiency in IECs sensitizes to TNF-induced damage of the small intestine and liver. (A) H&E histology on a section of the small intestine from A20^IEC-KO mice and control littermates (WT) 0 and 6 h after mouse TNF injection. Bars, 100 µm. (B) TUNEL staining on sections from small intestine 0 and 6 h after mouse TNF injection, staining apoptotic cells in red. Bars, 50 µm. (C) Caspase activity assayed on tissue homogenates of terminal ileum of A20^IEC-KO mice and WT littermates at 0 (control) and 90 min after mouse TNF injection. Error bars represent SEM. (D) H&E histology on liver samples from control (WT) and A20^IEC-KO mice 0 and 6 h after mouse TNF injection. Bars, 50 µm. Data are representative of two independent experiments.