Bone Morphogenetic Protein-15 (BMP-15) is an extracellular multifunctional signaling cytokine that is also a member of the TGFβ family. In the ovarian follicles, BMP-15 has a vital role in regulating the growth and maturation of follicles, the sensitivity of granulosa cells to FSH, and preventing granulosa cells from apoptosis. In addition, BMP-15 and GDF9 cooperate and have the same interaction on target cells.