CEACAM1 (BGP/CD66a) is a transmembrane glycoprotein which belongs to the carcinoembryonic antigen (CEA) gene family. It is expressed on cells of epithelial and myeloid origin and mediates homophilic intercellular interactions that influence cellular growth, immune cell activation, and tissue morphogenesis. CEACAM1 is a putative tumour suppressor based on diminished expression in some aggressive types of cancer cells. The anti-tumour effect may be due to inhibition of tumour angiogenesis, possibly by increased secretion of anti-angiogenic molecules from the cells. Like all members of the CEACAM family, it consists of a single N domain, with structural homology to the immunoglobulin variable domains, followed by two immunoglobulin constant-like A (A1, A2) and one B domain. While the N, A1 and B domains can also be found in other CEA-family members, the A2 domain of CEACAM1 differs from those found in other CEACAM.Synonyms: BGP, BGP1, Biliary glycoprotein 1, Carcinoembryonic antigen-related cell adhesion molecule 1