Figure 7. Akt inactivation rescues AEC senescence in vitro. After PTEN was stably knocked down, an inhibitor of the AKT pathway (20 μm/L LY294002 or 5 μg/ml MK2206) was added 1 hour before bleomycin (10 μg/ml) to A549 cells for 72 hours followed by a fresh medium transfer for 24 hours. (A, B) Rescue of cell senescence by LY294002 was determined by SA-β-Gal staining (original magnification, 200×), and decreased expression of P21WAF1 (C, D) was confirmed by western blot. Rescue of cell senescence by MK2206 was determined by SA-β-Gal staining (E, F) and P21WAF1 expression (G, H). Data are shown as the mean ± SEM, n ≥ 3 per group. *p < 0.05, **p < 0.01. One-way ANOVA followed by Dunnett’s Multiple Comparison Test.