Carcinoembryonic antigen (CEA) describes a set of glycophosphatidyl inositol and transmembrane cell-surface-anchored glycoproteins involved in cell adhesion, differentiation, anoikis, polarization, and tissue architecture. CEA staining, along with Calretinin, CK 5/6, D2-40, HBME-1, Napsin A, MOC-31, and Ber-EP4, is used to help differentiate between adenocarcinoma and mesothelioma. Staining with Anti-CEA is also suggested to be useful in identifying the origin of metastatic adenocarcinoma. CEA is an effective marker for adenocarcinomas of the lung, colon, stomach, esophagus, pancreas, gallbadder, urachus, salivary gland, ovary, and endocervix.