Carcinoembryonic (CEA / mCEA / pCEA) antigen includes a large class of proteins such as CEACAM5 that are have high expression in a variety of cancers. The degree of expression of CEA is correlated with tumor stage, with particularly pronounced levels in well-differentiated adenocarcinomas relative to early tumors. Staining is observed in normal epithelial cells of the colon, granulocytes, gallbladder, hepatocytes, prostate, and small intestine goblet cells, as well as thyroid and C cells. Positive staining has been observed in cancers of the bile duct, bladder, cervix, cholangiocarcinoma, colorectal cancer, endometrium, stomach, liver, lung adenocarcinomas, ovary, pancreas, salivary gland, medullary thyroid carcinoma, and others. Staining is expected to be membranous and cytoplasmic. References: Experimental Cell Research 324. 2014 June. (2):115–23, DOI:10.1016/j.yexcr.2014.04.007; Current Oncology (Toronto, Ont.). 2014 Feb. 21 (1):e1-7, PMID: 24523606; Med Arch. 2013 Dec;67(6):397-401, PMID: 25568506