TNFSF11 and Miyoshi myopathy: Specifically, BMSCs interact with MM cells and secrete high levels of interleukin-6 (IL-6), a major MM cell growth factor, osteoclast-activating cytokines such as IL-1β, tumor necrosis factor-α (TNFα), and the receptor activator of nuclear factor κB-ligand (RANKL), a key factor and dominant mediator of osteoclast differentiation, activation and survival [2, 3].