This gene encodes a protein that belongs to the CEA (carcinoembryonic antigen) family whose members are GPI (glycosyl phosphatidyl inositol) anchored cell surface glycoproteins. Members of this family play a role in cell adhesion and are widely used as tumor markers in serum immunoassay determinations of carcinoma. CEACAM6 affects the sensitivity of tumor cells to adenovirus infection. CEACAM6 acts as a receptor for adherent-invasive E. coli adhesion to the surface of ileal epithelial cells in patients with Crohn's disease. CEACAM5 encodes a cell surface glycoprotein that represents the founding member of the CEA (carcinoembryonic antigen) family of proteins. CEACAM5 is used as a clinical biomarker for gastrointestinal cancers and may promote tumor development through its role as a cell adhesion molecule. Additionally, CEACAM5 may regulate differentiation, apoptosis, and cell polarity.