DDZ inhibited IL-6-induced STAT3 activation in human multiple myeloma MM1.S cells. (A) MM1.S cells (1 × 106 cells/well) were stimulated with IL-6 (10 ng/mL) for the indicated time. Whole cell lysates were prepared, and western blotting was carried out against various proteins. (B)–(D) MM1.S cells (1 × 106 cells/well) were treated with 30 μM of DDZ for 0, 1, 2, and 3 h and then stimulated with IL-6 (10 ng/mL) for 10 min. Thereafter, western blotting was done. (E) MM1.S cells (2 × 106 cells/well) were transfected with STAT3-luciferase plasmid for 48 h, treated with DDZ (0–30 µM) for 3 h, and then stimulated with IL-6 (10 ng/mL) for 10 min. Thereafter, luciferase activity was measured. (F) A cell proliferation study was performed with an MTT assay. U266 and MM1.S cells (2 × 104 cells/well) were seeded onto a 96-well plate and incubated with 30 µM of DDZ for indicated time intervals. The results are presented as the mean ± SD. *** p < 0.001 compared the control. (G) U266, A549, DU145, Panc-1, MCF-7, and SNU-1 cells were treated with 30 μM of DDZ for 3 h, and western blotting was done. The results shown are representative of three independent experiments.