TNFRSF11B and plasma cell myeloma: Osteoclasts contribute to the survival and proliferation of myeloma cells by releasing the receptor activator of nuclear factor kappa-B ligand (RANKL), which is secreted by myeloma cells [101], osteoclasts [102], and BMSCs [103], and the abnormality of RANΚL-osteoprotegerin (OPG) pathway [104,105,106].