Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is also known as Biliary glycoprotein 1 (BGP1), CD66a, which belongs to the immunoglobulin superfamily or CEA family. CEACAM1 /CD66a contains three Ig-like C2-type (immunoglobulin-like) domains and one Ig-like V-type (immunoglobulin-like) domain. CEACAM1 /CD66a was described as an adhesion molecule mediating cell adhesion via both homophilic and heterophilic manners, and was detected on leukocytes, epithelia, and endothelia. Studies have revealed that CEACAM1 / BGP-1 performs actions in multiple cellular processes including tissue differentiation, angiogenesis, apoptosis, metastasis, as well as the modulation of innate and adaptive immune responses.