Ubiquitinating enzymes (UBEs) catalyze protein ubiquitination, a reversible process countered by deubiquitinating enzymes (DUB) action. There are five DUB subfamilies including the USP, UCH, OTU, MJD, and JAMM enzymes. Ubiquitinspecificprocessing protease 2 (USP2) belongs to the USP (UBP/UCH type 2) subfamily and is characterized by its C19 peptidase activity, which is involved in ubiquitin recycling and in the disassembly of various forms of polymeric ubiquitin and ubiquitin like protein complexes. There is mounting evidence that USP2 functions as an oncoprotein through multiple mechanisms. In human prostate cancer, USP2 is highly overexpressed and drives tumor growth by binding to and stabilizing fatty acid synthase through deubiquitination. It has also been demonstrated that USP2 can bind and deubiquitinate both Mdm2 and cyclin D1, which leads to their stabilization and enhanced cell proliferation.