Glycogen synthase kinase (GSK)-3β mobilizes to the nucleus of human primary mesenchymal cells (HPMCs) undergoing mesothelial mesenchymal transition (MesoMT). Serum-starved HPMCs were treated with phosphate-buffered saline (PBS), 5 ng/mL transforming growth factor (TGF)-β, 7 nmol/L plasmin (PLN), or 20 nmol/L urokinase plasminogen activator (uPA) (for 24 and 48 hours). A: PBS-, TGF-β–, and uPA-treated cells (24 hours) were immunofluorescently labeled for GSK-3β (green) and nuclei (red). Colocalization of GSK-3β and nuclei appear orange. Arrows indicate the location of the nucleus. B: PBS-, TGF-β–, plasmin-, and uPA-treated HPMCs were lyzed and resolved by SDS-PAGE. Lysates were probed for α-smooth muscle actin (α-SMA), total GSK-3β, and Tyr-216–phosphorylated GSK-3β (pGSKT) by Western blot analysis. Akt was used as loading control. n = 30 fields per slide (A); n = 3 slides per treatment (A); n = 2 independent experiments (B).