Abstract: The Ubiquitin-specific protease 2, USP2) gene encodes three different isoforms,USP2a, USP2b and USP2c, due to alternative splicing of the 5' USP2 exons. USP2 is an important deubiquitinating enzyme. It deubiquitinates the target protein and protects it from degradation.It's implicated in the regulation of the cell cycle, circadian, and other biological events. Ectopic expression or inhibition of USP2 causes the accumulation or degradation of its specifi c substrate in a dose-dependent manner, which are implicated in tumor genesis, growth, and progression. High expression of USP2 exhibits oncogenic behavior in cultured cells which may promote tumorigenesis, but it also plays an important role on apoptosis elicited by TNF. The inconsistent results may be related to different isoforms of USP2 and its different ubiquitin chains with substrate protein in tumors. However, further investigation is still needed.