Ac p53

After washing, cold RIPA with protease inhibitors (Roche) was used to lyse cells for 15 min. Then, after centrifugation, the cell supernatant was kept frozen at −80°C until use. Bradford assays (Bio-Rad Laboratories; CA, USA) were employed to assess protein concentrations. Samples (20 μg) were separated via SDS-PAGE, after which dry transfer to nitrocellulose membranes was conducted. After being blocked in 5% BSA for 1 h, primary antibodies were used to probe the membranes overnight at 4°C, including antibodies targeting human SIRT1, acetylated-p53 at K382 (Ac-p53), p21, forkhead box O1 (FoxO-1) (Cell Signaling Technology; USA), Ac-FoxO-1, total p53 (1: 2000 dilution), and senescence marker protein-30 (SMP-30) (all from Santa Cruz Biotechnology). β-actin served as an internal control and was purchased from Sigma Aldrich. After incubation with the appropriate secondary antibodies (1: 10 000 dilution; GE Healthcare, Buckinghamshire, UK), the immunostained protein bands were visualized with an ECL system (ProteinSimple; Santa Clara, USA), followed by quantification using ProteinSimple image software. All samples had 3 biological replicates, and each biological replicate was assayed in duplicate; therefore, the data for each time point are an average of 6 individual replicate runs. Representative images of the immunostained bands are presented in the figures.