PLK1 and prostate cancer: found high PLK1 expression in CRPC cells such as prostate cancer cell line 3 (PC3), Duke University 145 (DU145), and lymph node carcinoma of the prostate (LnCAP), but not in prostate epithelial cells (PrEC) normal prostate epithelial cells, and PLK1 knockdown in CRPC cells caused cell cycle arrest but not in prostate epithelial cells.