Carcinoembryonic antigen related cell adhesion molecules 1 and 5 (CEACAM1 and CEACAM5) are members of the carcinoembryonic antigen (CEA) gene family, which belongs to the immunoglobulin superfamily. CEACAM1 was originally described in bile ducts of liver as biliary glycoprotein. Subsequently, it was found to be a cell-cell adhesion molecule detected on leukocytes, epithelia, and endothelia. 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.