BMPR1B, a member of the bone morphogenic protein (BMP) receptor family of transmembrane serine/threonine kinase, belongs to the transforming growth factor-β (TGF-β) superfamily [16], whose members are dynamically expressed in the endometrium during menstruation, pregnancy, and endometriosis [17]–[19]. Here, TGFB1 is linked to endometriosis.