TGFB1 and osteoporosis: Another TGF-β superfamily member, activin A, is an important positive RANKL-induced osteoblastogenesis receptor activator, in which Spad-mediated signaling is essential for the induction of osteoclast development and function, activin A may be a good candidate for the treatment of CKD-induced osteomalacia or osteoporosis and is expected to be a new therapeutic target for osteoporosis (Sugatani, 2018).