TNFSF11 also known as RANKL, is a member of the tumor necrosis factor (TNF) cytokine family which is a ligand for osteoprotegerin and functions as a key factor for osteoclast differentiation and activation. RANKL is a polypeptide of 217 amino acids that exerts its biological activity both in a transmembrane form of about 40-45 kDa and in soluble one of 31 kDa (PMID: 15308315). The membrane-bound RANKL (mRANKL) is cleaved into a sRANKL by the metalloprotease-disintegrin TNF-alpha convertase (TACE) or a related metalloprotease (MP). RANKL induces osteoclast formation through its receptor, RANK, which transduces signals by recruiting adaptor molecules, such as the TNF receptor-associated factor (TRAF) family of proteins. RANKL was shown to be a dentritic cell survival factor and is involved in the regulation of T cell-dependent immune response. T cell activation was reported to induce expression of this gene and lead to an increase of osteoclastogenesis and bone loss. RANKL was shown to activate antiapoptotic kinase AKT/PKB through a signaling complex involving SRC kinase and tumor necrosis factor receptor-associated factor (TRAF) 6, which indicated this protein may have a role in the regulation of cell apoptosis.