The carcinoembryonic antigen (CEA) family: structures, suggested functions and expression in normal and malignant tissues.

The human CEA family has been fully characterized. It comprises 29 genes of which 18 are expressed; 7 belonging to the CEA subgroup and 11 to the pregnancy specific glycoprotein subgroup. CEA is an important tumor marker for colorectal and some other carcinomas. The CEA subgroup members are cell membrane associated and show a complex expression pattern in normal and cancerous tissues with notably CEA showing a selective epithelial expression. Several CEA subgroup members possess cell adhesion properties and the primordial member, biliary glycoprotein, seems to function in signal transduction or regulation of signal transduction possibly in association with other CEA sub-family members. A modified ITAM/ITIM motif is identified in the cytoplasmatic domain of BGP. A role of CEA in innate immunity is envisioned.