Carcinoembryonic antigen
Carcinoembryonic antigen (CEA) is a glycoprotein involved in cell adhesion. It is normally produced during fetal development, but the production of CEA stops before birth. Therefore, it is not usually present in the blood of healthy adults, although levels are raised in heavy smokers. CEA was first identified in 1965 in human colon cancer tissue extracts by [Phil Gold]] and Samuel O. Freedman. It was later found that serum from individuals with colorectal and other carcinomas had higher levels of CEA than healthy individuals and is used to monitor the response to colon cancer treatment.
CEA and related genes make up the CEA family belonging to the immunoglobulin superfamily. In humans, the carcinoembryonic antigen family consists of 29 genes, 18 of which are normally expressed.