NFKB1 and plasma cell myeloma: Additionally, the deubiquitinase CYLD, which negatively regulates NF-κB activation by removing K63-linked polyubiquitin chains from IKKγ, TRAF2, and TRAF6, is frequently inactivated by deletion, mutation, or transcriptional silencing in multiple myeloma [19,20,184,185,186].