CNF1 induces senescence in GL261 cells: SA-beta-gal staining. (A) Representative images of SA-beta-gal staining of GL261 cells after 24 h, 48 h and 72 h of CNF1 treatment. All images were taken at 20× magnification. Scale bar = 10 μm. Inset: representative high magnification of a CNF1-treated cell at 48 hours. Scale bar = 5 μm. (B) Percentage of beta-gal positive cells at the different time points. Data shown are representative of three independent experiments (one way ANOVA, p < 0.0001). All data represent means ± SEM.