IL3 and plasma cell myeloma: Myeloma cells (MCs) secrete several cytokines, including the receptor activator of NF-κB ligand (RANKL), interleukin-3 (IL-3), IL-6, and activin A to activate osteoclasts (OCs), and secrete dickkopf-1 (DKK1) and soluble frizzled related proteins (SFRPs) to inhibit the differentiation and maturation of osteoblasts (OBs) [2]–[7].