NFKB1 and plasma cell myeloma: Mechanistically, first and second generation proteasome inhibitors triggers apoptosis in myeloma cells that is associated with enhanced expression of proapoptotic genes like p53, p21, Noxa, Puma, and E2F, downregulation of antiapoptotic genes, activation of caspases cascade and the inhibition of NF-κB signaling by blocking degradation of the NF-κB inhibitor IκB.