SMAD7 and Crohn disease: S. Sana et al. proposed a relationship between SMAD proteins and TGFβ signaling, in which high SMAD7 immunoreactivity and a lack of p-SMAD3 expression caused defective TGFβ signaling in environmental enteropathy [27]; this was similar to a previous result in inflammatory bowel disease and Crohn’s disease [28].