SMAD4 and cancer: The mechanisms of upregulation of MUC5AC in cancers include promoter hypomethylation, inflammatory interleukins, TGFβ/Smad4, HIF1α, COX2, and GLI1.34‐39 TFF1 has been shown to be regulated by GATA6 in the colon40 and is a target gene for estrogen receptor–mediated signaling in mammary epithelium.41