Five human myeloma cell lines (MM1.S, MOLP-8, RPMI-8226, U266 and H1112) were used for these experiments. Cells were maintained in RPMI 1640 medium (Corning Cellgro®, Manassas, VA, USA) with L-glutamine supplemented with 5% fetal bovine serum and 1% penicillin/streptomycin. Cell lines were authenticated using the University of Texas MD Anderson Characterized Cell Line Core using the short-tandem-repeat method. Drug-resistant (bortezomib, carfilzomib, doxorubicin and lenalidomide) cell lines were generated as described previously (Bjorklund, et al 2011 (link), Dalton, et al 1986 (link), Kuhn, et al 2009 (link)). Isogenic MM1.S and MOLP-8 TP53 WT and KO cell lines were generated using sequence-specific zinc-finger nucleases (ZFNs; CompoZr® Knockout ZFNs; Sigma Aldrich, St. Louis, MO, USA) targeting either a non-specific sequence or exon 7 of the TP53 DNA binding domain. MYC overexpression was accomplished using a pCDH-puro-cMyc plasmid, which was a gift from Jialiang Wang (Addgene plasmid # 46970, Addgene, Cambridge, MA, USA) (Cheng, et al 2013 (link)), and transduced using a pCDH Lentiviral expression system (Systems Biosciences, Mountain View, CA, USA). Primary myeloma patient samples were purified using magnetic CD138 micro beads (Miltenyi Biotec Inc, San Diego, CA, USA). All primary patient samples were acquired with approval from the Institutional Review Board at the University of Texas MD Anderson Cancer Center after informed consent was obtained in compliance with the Declaration of Helsinki.