PTEN and ovarian cancer: It was shown that miR-17 could promote CRC cell proliferation and metastasis by targeting transforming growth factor-β receptor 2.[28]MiR-17 could induce drug resistance in CRC cells and negatively regulate PTEN expression.[29] miR-17 was reported to promote hepatocellular carcinoma cells through p38 mitogen-activated protein kinase-heat shock protein 27 pathway.[30] MiR-17 could promote normal ovarian cancer cells to CSC development via suppression of the lkb1-p53-p21/waf1 pathway, but whether it was true in CRC was unknown.