In addition, in a PCOS rat model, exosomes derived from adipose stem cells carried miR-21-5p into hepatocytes, targeted the BTG antiproliferation factor 2 (Btg2), and induced the cAMP-response element binding protein (CREB) in hepatocytes to bind to the CREB cis element on the target gene promoter. This evidence concerns the gene CREB1 and polycystic ovary syndrome.