SMAD4 and colorectal carcinoma: Carcinoembryonic antigen-associated cell adhesion molecule 5 (CEACAM5), a highly glycosylated protein of the CEACAM family, reduces the expression of TGF-β pathway members (TGFBR2, SMAD4, and SPTBN1), which alters the colonic microbiome to promote CRC [40].