Effect of IL-6 treatment on the expression of APM components LMP2 and LMP7 in premalignant and malignant BM plasma cells. indicates MGUS patients; and , MM patients. Samples were incubated without or with 100 ng/mL IL-6 for 36 hours before immunostaining and flow cytometry analysis (A,B,D,E) or mRNA extraction and quantification (C,F). IL-6 treatment significantly reduced levels of LMP2 and LMP7 protein (P < .001, Wilcoxon signed rank test) and down-regulated the corresponding transcripts in both MGUS and MM samples (P < .05, Wilcoxon signed rank test).