Loss of digestive organ expansion factor ( reveals an essential role during murine embryonic development that is independent of p53.

Increased levels of inhibitors of the p53 tumor suppressor such as Mdm2 and Mdm4 drive tumor development and thus serve as targets for therapeutic intervention. Recently, digestive organ expansion factor (Diexf) has been identified as a novel inhibitor of p53 in zebrafish. Here, we address the potential role of Diexf as a regulator of the p53 pathway in mammals by generating knockout mice. We demonstrate that, similar to and , homozygous deletion of is embryonic lethal. However, unlike in and mice, loss of p53 does not rescue this phenotype. Moreover, heterozygous animals are not sensitive to sub-lethal ionizing radiation. Thus, we conclude that is an essential developmental gene in the mouse, but is not a significant regulator of the p53 pathway during development or in response to ionizing radiation.