Phosphorylation of STAT-6 by IL-4 and IL-4/GM-CSF in huASMC. Starved huASMC were incubated with either BSA vehicle control (1 μg/ml), IL-4 (0.5 nM), GM-CSF (0.4 nM), or IL-4/GM-CSF (0.5 nM/0.4 nM) for 15 minutes. Standard Western blot analyses were performed to detect STAT-6 and phosphorylated-STAT-6 (p-STAT-6) using a anti-STAT-6 polyclonal rabbit antibody (Calbiochem) and anti-p-STAT-6 polyclonal rabbit antibody (Calbiochem). Anti-rabbit horseradish peroxidase linked antibody was used as the secondary antibody. Protein bands were detected by ECL. STAT-6 was abundantly expressed by all four groups, while p-STAT-6 was only expressed in the IL-4 and IL-4/GM-CSF groups. Fibronectin polyclonal rabbit antibody (Sigma) was used as an irrelevant isotype control and was abundantly expressed in all four groups.