Carcinoembryonic antigen: cell adhesion molecule and useful diagnostic marker.

Carcinoembryonic antigen (CEA) was first identified over 30 years ago as a marker of malignant colonic cells, but has since been shown to be expressed by a range of normal epithelial cells. Moreover, CEA is one member of a larger gene family and shares structural homology with other family molecules. Despite this confused picture, CEA is now known to function in several biological roles, including cell-cell adhesion. Its use in the diagnostic setting has also changed over the years, where in routine immunohistochemistry, monoclonal antibodies to CEA are useful in aiding diagnosis when used as part of a panel. Here, recent advances in understanding the biological role(s) that CEA and CEA-related antigens may play in cell adhesion are highlighted, together with results from molecular studies that illustrate how structure can influence the choice of CEA antibodies for use in both the research and diagnostic laboratory.