22Rv1 cells with Dox-inducible knockdown of PRMT5 (shPRMT5), pICln (shpICln) or scramble control (shSC) were injected subcutaneously into right flanks of surgically castrated male NRG mice. Tumor-bearing mice were treated with doxycycline in drinking water once tumors reached ~100 mm3. A-B, Tumor growth curves were determined and compared between treatment groups (ANOVA; ****, P < 0.0001). C-G, At the end of treatment, tumors were resected and probed for cleaved caspase-3 and Ki-67 using IHC. Presented are representative images (C) and the quantification of the percentage of positively stained cells out of the total number of cells (D-G). Scale bar indicates 40 μm. Results are mean ± SD (n = 10 per group). D-G, Student’s t-test was performed to determine statistical significance. ns P > 0.05, ** P < 0.01, *** P < 0.001.