PTEN and ovarian cancer: miR‐21a‐5p has been reported previously as overexpressed in ovarian tumors by multiple studies20, 24 and is being tested for potential use as a circulating tumor biomarker for ovarian cancer detection.25 In addition, a recent study has found that miR‐21a‐5p plays a role in epithelial to mesenchymal transition, demonstrating its oncogenic potential.21 Therefore, the effects of PTEN knockdown in tumorigenesis may be also mediated by this miRNA.