SMAD3 and stricture: The immunohistochemical results showed that the protein expression levels of Smad3 and NF-κB were higher than those of normal intestinal tissues, and Smad3 was mainly expressed in the mucosal epithelium, submucosa, and muscular layer, suggesting that Smad3 and NF-κB proteins are likely involved in the occurrence of NEC secondary to intestinal stenosis.