SOST and plasma cell myeloma: Because muscular SOST expression is higher in patients with multiple myeloma and sarcopenia than in control subjects [56] and circulating sclerostin levels are negatively correlated with skeletal muscle mass [57], it is tempting to speculate that sclerostin may have an inhibitory effect on muscle cell proliferation and differentiation by impairing balanced canonical Wnt/β-catenin signaling which regulates skeletal muscle regeneration and myogenesis [58].