Importantly, AHR signaling on the intestinal epithelium as opposed to leukocytes was required for the protection from NEC, as AhrΔIEC mice had more severe NEC compared to wild-type mice (Fig. 2j–m), while NEC severity was not different between wild-type mice and AhrΔlys mice which lack AHR on leukocytes, but which express AHR on the intestinal epithelium (as seen in Supplementary Fig. 1). This evidence concerns the gene AHR and necrotizing enterocolitis.