CDX2 antibody is a homeobox gene that encodes an intestine-specific transcription factor. It is expressed in the nuclei of epithelial cells of the intestine, from duodenum to rectum. Studies have shown that CDX2 is a sensitive marker for colonic carcinoma metastatic to the ovary and is more specific than CK20 as it is not expressed by serous and endometrioid carcinomas. CDX2 is also expressed in mucinous ovarian carcinomas but not expressed in normal gastric mucosa. CDX2 was reported to be advantageous over CK20 for distinguishing primary ovarian tumors from metastases of upper gastrointestinal tract origin.