Pirh 2 (P53 induced RING-H2 protein), also known as RCHY1, it forms dimers through its N- and C-terminus in cells. The Pirh2 has ubiquitin-protein ligase activity and it binds with p53 and promotes the ubiquitin-mediated proteosomal degradation of p53. The Pirh2 is oncogenic because loss of p53 function contributes directly to malignant tumor development. Pirh2 expression decreases the level of p53, and a decrease of endogenous Pirh2 expression increases p53 levels. Pirh2 is therefore considered, together with MDM2, to act as a negative regulator of p53 function.