The function of ENSG00000198625 (MDM4, MDM4 regulator of p53) is as follows. Contributes to p53/TP53 regulation (PubMed:32300648). Inhibits p53/TP53- and p73/TP73-mediated cell cycle arrest and apoptosis by binding their transcriptional activation domains. Inhibits degradation of MDM2. Can reverse MDM2-targeted degradation of TP53 while maintaining suppression of TP53 transactivation and apoptotic functions. {ECO:0000269|PubMed:16163388, ECO:0000269|PubMed:16511572, ECO:0000269|PubMed:32300648}.