It appears that there is a reciprocal regulation of miR-421 and MEG3, as the forced expression of MEG3 inhibits the level of miR-421 in OCSCs [54], and overexpression of miR-421 results in a reduction in MEG3 and platelet-derived growth factor receptor A (PDGFRA) in ovarian cancer stem cells [56]. This evidence concerns the gene MEG3 and ovarian cancer.