PTEN and prostate cancer: Various tissue-specific studies show PTEN was negatively regulated by several miRNAs, e.g., miR-21, miR-221 and miR-222 in gastric cancer[97,98]; miR-93 in ovarian cancer[99]; miR-519d in liver cancer[100]; miR-214 in non-small cell lung cancer[101]; and miR-153[102] and miR-21[103] in prostate cancer.