In 2019, Jun Zhai reported that metformin could improve ER by downregulating expression of miR-491-3p and miR-1910-3p, thereby increasing expression of HOXA10 and ITGB3, known as important endometrial receptive markers, in the endometrium of PCOS women [75–77]. The gene discussed is HOXA10; the disease is polycystic ovary syndrome.