NFKB1 and Marchiafava-Bignami disease: Another essential signaling pathway that correlates with the development of myeloma bone disease (MBD) is the receptor activator of nuclear factor κB (RANK)/ligand of RANK (RANKL) pathway, which stimulates the signals via NF‐κB and MAPK pathway providing the development, maturation, and differentiation of osteoclast precursors [55].