The overexpression of miR-21 in bone marrow-derived mesenchymal stem cells adherent to MM cells contributes to bone metastasis by enhancing the activation of the STAT3-mediated receptor activator of NF-κB ligand RANKL and mediating RANKL-induced osteoclastogenesis [70]. The gene discussed is TNFSF11; the disease is Miyoshi myopathy.