FIGURE 1.

GSK-3β inhibitors increase GSK-3β phosphorylation and decrease GSK-3β activity. A, human airway smooth muscle cells were treated with LiCl (10 mm), CT-1 (10 ng/ml), and TGF-β (10 ng/ml). Representative immunoblots for phospho-GSK-3β and total GSK-3β are shown. LiCl, CT-1, and TGF-β increased the level of phospho-GSK-3β without affecting that of total GSK-3β. SB216763, a GSK-3β kinase inhibitor, had no effect. B, A7R5 vascular smooth muscle cells were treated with LiCl, SB216763, CT-1, or TGF-β and lysed. Lysates were immunoprecipitated and assayed for GSK-3β activity in a reaction containing the GSK-3β substrate Tau (1 μg/μl), ATP (1 mm), and [γ-³²P]ATP (10 μCi). Total GSK-3β of immunoprecipitates is also shown. In the first example shown, the IgG heavy chain apparently migrated just behind GSK-3β, leaving a “ghost band” and creating the impression of a doublet. For this panel, the control and SB216763 bands are from different parts of the same gel. Results are representative of three separate experiments.