The suppressive function of CDX2 on tumor cell proliferation observed in several studies [28-30] has been explained by CDX2-mediated activation of negative cell cycle regulators, such as cyclin-dependent kinase inhibitor 1A (CDKN1A), a known inhibitor of G1 cyclin/cyclin-dependent kinase complexes [6]. This evidence concerns the gene CDKN1A and neoplasm.