Inhibition of the Otub1/c-Maf axis by LanC induces MM cell apoptosis. (A) MM cells were incubated with LanC overnight, followed by IB assays. (B) RPMI-8226 cells were transfected with siOtub1 for 48 hours, followed by LanC treatment and IB assays. (C) MM cells were incubated with LanC overnight, followed by Annexin V/PI staining and flow cytometric analysis. (D) MM cells were transfected with siOtub1 alone or with c-Maf for 48 hours, followed by Annexin V-FITC staining and flow cytometric analysis (n = 3). (E) Bone marrow mononuclear cells from patients with MM (n = 23) or HDs (n = 5) were mixed in LanC (10 nM)–containing MethoCult medium and cultured in 3.5-cm dishes for 14 days before colony counts. (E) Based on the c-Maf measurement of qRT-PCR results, 23 patients with MM from panel D were divided into 3 groups (c-Maf^low, c-Maf^mid, and c-Maf^hi); colonies were then statistically analyzed. (F) RPMI-8226 and MM1.S cells were transfected with c-Maf, followed by LanC treatment of 24 hours and IB assays. (G) The Cle-PARP/Pro-PARP ratios from panel F were quantified. *P < .05; **P < .01. NS, not significant.