Figure 9. A proposed model depicting the involvement of the eNOS/cGMP/PKG pathway in PF activation. In response to NO synthesized by eNOS in oocytes and preGCs, cGMP and PKG are activated and downregulates FBXW7 in preGCs, thus diminishing FBXW7-induced ubiquitination/degradation of mTOR. This process triggers the transduction of KITL/KIT/PI3K/AKT/FOXO3a signaling, links the communication between preGCs and oocytes, and consequently awakens dormant PFs.