PLK1 and prostate cancer: Interestingly, NOD/SCID/γcnull (NSG) mice engrafted with PLK1-overexpressing prostate epithelial cells developed not only primary tumors, but also lung micrometastases, which suggests that PLK1 overexpression not only leads to the oncogenic transformation of prostate epithelial cells, but may also drive prostate cancer metastasis [47].