MM cell lines (MM.1S, MM.1R, RPMI8226, INA6, Dox40, LR5, ARP1) and peripheral blood mononuclear cells from normal healthy donors were cultured in RPMI-1640 medium containing 10% fetal bovine serum and antibiotics. ANBL6 cells were kindly provided by Dr Robert Orlowski (Houston, TX, USA).45 (link) Tumor cells, BMSCs and pDCs were cultured as described previously.28 (link),29 (link) Helsinki protocol was followed for obtaining informed consent from all patients. Bortezomib, dexamethasone, lenalidomide or pomalidomide were obtained from Selleck Chemicals LLC (Houston, TX, USA), and OPA was obtained from Calbiochem (San Diego, CA, USA). Recombinant DUBs were obtained from Creative BioMart (Rpn11/ PSMD14, Shirley, NY, USA), Boston Biochem (USP1, USP7, Cambridge, MA, USA) and LifeSensors Inc. (USP2, USP4, USP5, USP8, USP20, Uch37, Malvern, PA, USA).