TNFSF11 and plasma cell myeloma: Bone resorption in patients with multiple myeloma is thought to be mediated by a number of cytokines, including receptor activator of nuclear factor kappa -B ligand (RANKL), macrophage inflammatory protein (MIP) 1α and tumour necrosis factors (TNFs) which are either secreted by the myeloma cells or by other accessory cells involved in cell-cell interactions within the marrow micro-environment [15].