CDX2, a homeobox domain-containing transcription factor, is a master regulator of the trophectoderm, the layer that gives rise to extra-embryonic tissues in mammalian development. CDX2 is also involved in intestinal development, and gain of expression or loss of expression has been associated with various human malignancies, such as Barrett's esophagus and colorectal cancer. Mouse embryonic stem cells deficient in CDX2 display limited hematopoietic progenitor development and altered Hox gene expression, pointing to a role for CDX2 in Hox gene regulation. CDX2 is also implicated in the aberrant expression of Hox genes in human AML cell lines.