TNFSF11 and osteoporosis: Another success story was the discovery of RANKL, the subsequent identification of its role in osteoclast development, and function (e.g. identified using transgenic animal models), and finally the clinical use of denosumab [10, 11], an anti-RANKL antibody, for the treatment of not only osteoporosis, but also other bone diseases characterized by increased bone resorption [12].