The caudal-related homeodomain protein 2, CDX-2, is a transcription factor which is expressed in the intestine and is thought to play an important role in the proliferation and differentiation of intestinal epithelial cells. The CDX-2 protein is expressed in primary and metastatic colorectal carcinomas, intestinal metaplasia of the stomach and intestinal type gastric cancer. In human colorectal cancer, the expression of both CDX2 and carbonic anhydrase 1, a gene regulated by CDX2, is reduced or absent. CDX-2 is one of the important regulators in defining pathways for coordinate control of drug metabolism in the gastrointestinal tract.