SOST and osteoporosis: Two such paracrine factors are RANKL (also known as tumor necrosis factor ligand superfamily member 11 [TNFSF11]), which drives osteoclastogenesis, and sclerostin (encoded by the gene SOST), which inhibits osteoblast activity.(13) Agents that inhibit RANKL (denosumab),(14) or sclerostin (romosozumab),(15, 16) are in use for the treatment of osteoporosis.