While Zhang et al. showed that up-regulation of miR-21 is associated with down-regulated glucose transporter 4 (Glut4) and increased insulin resistance using a rat polycystic ovary syndrome model17, Ling et al. demonstrated that miR-21 reverses high glucose and high insulin-induced insulin resistance in 3T3-L1 adipocytes through promoting the translocation of Glut4 to plasma membrane18. Here, SLC2A4 is linked to polycystic ovary syndrome.