USP21 and prostate cancer: In sharp contrast, Priolo et al. demonstrated that USP2-1 siRNA increased the apoptosis rate in the prostate cancer cell lines LNCaP (androgen dependent, wild type p53) and DU145 (androgen independent, mutant p53), but not PC-3 (androgen independent, p53-null), suggesting an anti-apoptotic role of USP2-1 [75].