Effects of IL-4, IL-13 and IFN-γ pre-treatment in STAT6 phosphorylation and total STAT6 protein induced by IL-13. HASM cells were pre-treated with various concentrations of IL-4 (n = 3), IL-13 (n = 3) or IFN-γ (n = 5) for 24 hours and then stimulated with IL-13 (5 ng/ml) for 30 minutes. Whole cell lysates were extracted and subjected to Western analysis using antibodies that recognize total and phosphorylated forms of STAT6. A: Representative Western blot films. B. Detected phosphorylated – STAT6 band densities were measured and the densitometric values were normalized to the IL-13-stimulated value. Data are shown as the mean values ± SEM of 3–5 independent experiments. * p < 0.05 compared to IL-13 stimulated value in the absence of cytokine pre-treatment.