TNFRSF11B and plasma cell myeloma: In this complex process, osteoblastogenesis-specific factors, like Dickkopf-1 (DKK1) and Runt-related transcription factor 2 (Runx2), and osteoclastogenesis-specific ones, like nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG), are stimulated or inhibited by MM cells and establishes a positive feedback that sustains myeloma cell survival and subsequently causes continuous bone destruction [5].