The gene CDX2 regulates several essential processes in the development and function of the lower intestinal epithelium, as well as in the vertebrate embryonic development (that starts with the fertilization of an egg cell by a sperm cell) where it becomes active in endodermal cells that are posterior to the developing stomach.
In common with the two other Cdx genes, CDX2 regulates several essential processes in the development and function of the lower gastrointestinal tract (from the duodenum to the anus) in vertebrates. In vertebrate embryonic development, CDX2 becomes active in endodermal cells that are posterior to the developing stomach. These cells eventually form the intestinal epithelium. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm cell, (spermatozoon). 
