Concentration-dependent effect of IL-13 on STAT6 phosphorylation. HASM were stimulated with IL-13 for 30 minutes. Levels of phosphorylated STAT6 in cell lysates were detected by Western blot analysis using antibody that recognizes the tyrosine-phosphorylated forms of STAT6. A: representative Western blot film. B: Detected phosphorylated STAT6 band densities were measured and densitometric values presented as mean values ± SEM of two independent experiments.