Stat3 inhibition induces growth arrest and cell death in human MM cell lines. (A) Immunoblot analysis of Stat3, pStat3-Y705, cyclin D1, cyclin D2 and survivin in human MM cell lines treated for 24 h with S3I-201 (RPMI-8226, 100 μM; H929 and EJM, 50 μM). β-actin levels are shown as loading control. (B-D) Quantification of cell growth and cell death of H929 (B), RPMI-8229 (C) and EJM (D) cells at various time points following treatment with S3I-201 at the indicated concentrations. Graphs are representative of two independent experiments.