MAP3K7 and Crohn ileitis: Adult mice harboring intestinal epithelial-specific Tak1 deletion on Tnfr1−/− background do not show observable health problems.14 However, the Tak1-deficient intestine still exhibits increased apoptosis in the crypt of the ileum and milder inflammatory conditions, which are similar to human ileitis.3 ROS are highly increased in the Tak1-deficient intestinal epithelium even on a Tnfr1−/− background.3 Furthermore, we found that almost no Paneth cells were observed in the Tak1-deficient small intestine (shown in the current study).