USP19 and prostate cancer: In the second pattern, demonstrated in three prostate cancer cell lines (DU145, PC-3, 22RV1) and in the immortalized breast normal epithelial cell line, USP19 conserved its ability to positively regulate cell growth through stimulation of progression through G1 into S phase and enhanced the rate of degradation of p27Kip1 (Figs. 1, 2, 4A).