BMP-4 inhibits IL-6–induced Stat3 phosphorylation in IL-6–dependent myeloma cell lines.

Cells were incubated for 4 hours with cytokines in concentrations (ng/mL) as indicated. Cellular lysates were analyzed by Western blot. The lower panels show the total Stat3 protein staining, and the upper panels show specific tyrosine phosphorylation of Stat3 amino acid residue 705.