Vaginal smear detection of the estrous cycle in mice showed that the estrous cycle was almost stalled in the diestrus or metestrus phase in the mice of the USP25+/+ DHEA group, while the USP25–/– DHEA group showed restoration of part of the cycle (Supplementary Figure 2), indicating that the estrous cycle was partially restored in the mice with PCOS after the knockout of USP25. This evidence concerns the gene USP25 and polycystic ovary syndrome.