Effect of cytokine inhibitors on the induction of HAMP promoter activity by MM patient sera. HuH7 cells were cotransfected with WT-HAMP promoter-firefly luciferase construct and pTK-RL construct. Next, cells were treated with indicated doses of cytokines or 10% serum with or without cytokine inhibitors. After treatment, cells were lysed and luciferase activity was measured. (A) Specificity array of the cytokine inhibitors. All results are expressed as percentage promoter activity. Bars represent mean ± SD of at least 3 independent experiments executed in duplicate. Statistical significance was determined with the Student t test or Mann-Whitney rank-sum test; *P < .05, and †P < .001, compared with the cytokine-only group (cytokine/vehicle). (B) The effect of cytokine inhibitors on the induction of the WT-HAMP promoter by MM or healthy sera. Anti–BMP-2/4 and noggin-Fc significantly reversed the stimulatory effect of MM sera. Results are expressed as fold induction over untreated control (vehicle/optimem). Bars represent mean ± SD. Statistical significance was determined with 1-way ANOVA to compare the same sera for the different cytokine inhibitors. To compare MM patient sera with normal sera within the same group, the Mann-Whitney rank-sum test was used; *P < .05, compared with untreated control (vehicle/optimem), and †P < .05, compared with serum only group (vehicle/serum).