IL-11-induced STAT3 phosphorylation depends on IL-11R stalk length.
A, Ba/F3–gp130–IL-11R, Ba/F3–gp130–IL-11RΔD341_L372, Ba/F3–gp130–IL-11RΔQ339_L372, Ba/F3–gp130–IL-11RΔE337_L372, and Ba/F3–gp130–IL-11RΔE335_L372 cells were either stimulated with 10 ng/ml IL-11 for 15 min or left untreated. STAT3 phosphorylation was determined by Western blotting. Total STAT3 and IL-11R were visualized within the cell lysate. β-actin was determined to ensure equal protein loading. The ratio of pSTAT3/STAT3 was determined from three independent experiments. B, Ba/F3–gp130–IL-11RΔD341_L372 cells were stimulated with either 10 ng/ml Hy–IL-6, 10 ng/ml IL-11 for the indicated time points, or left untreated. The relative amounts of SOCS3 mRNA were quantified by quantitative real-time PCR. Values were normalized to GAPDH (n = 3 independent experiments, three technical replicates per experiment, mean ± S.D.). C, the experiment was performed with Ba/F3–gp130–IL-11RΔE335_L372 cells as described in B.