MDM4（MDM4， p53 regulator），癌症关联基因，基因ID：4194，该基因编码一种核蛋白，在N端含有一个p53结合域，在C端含有一个环指结构域，与p53结合蛋白mdm2结构相似。这两种蛋白结合p53肿瘤抑制蛋白并抑制其活性，已被证明在多种人类癌症中过表达。然而，与降解p53的MDM2不同，这种蛋白通过结合其转录激活域抑制p53。该蛋白还通过环指域与MDM2蛋白相互作用，抑制后者的降解。因此，该蛋白可以逆转p53的MDM2靶向降解，同时维持p53的激活和凋亡功能的抑制。另外，编码不同亚型的剪接转录变异体也被发现有这种基因。This gene encodes a nuclear protein that contains a p53 binding domain at the N-terminus and a RING finger domain at the C-terminus， and shows structural similarity to p53-binding protein MDM2. Both proteins bind the p53 tumor suppressor protein and inhibit its activity， and have been shown to be overexpressed in a variety of human cancers. However， unlike MDM2 which degrades p53， this protein inhibits p53 by binding its transcriptional activation domain. This protein also interacts with MDM2 protein via the RING finger domain， and inhibits the latter's degradation. So this protein can reverse MDM2-targeted degradation of p53， while maintaining suppression of p53 trans。