TLR4 and necrotizing enterocolitis: One plausible explanation for the unexpected colocalization of TLR4 and IAP in control ileum resection specimens, as well as the lower expression of TLR4 in the enterocyte membrane seen in intestinal resection specimens stemming from NEC patients, is that TLR4 and IAP are consistently co-localized in the apical membrane of enterocytes.