Fig. 5.

CHK2 is a master regulator of SIRT1 deficiency-induced impairments on cell. a Fluorescence-activated cell sorting (FACS) analysis of mitotic index in HELA cells stably expressing control, Sirt1 short hairpin RNA (shRNA), Chk2 shRNA, Chk2 shRNA, and Sirt1 shRNA treated with or without 100 μM hydrogen peroxide (H₂O₂) for 1 h. Statistical differences were analyzed using Student’s t tests. Error bars represent ± SD. **P < 0.01. Protein expression was examined by western blot with indicated antibody (right). b Morphological analysis of HELA cells stably expressing control and Sirt1 shRNA either untreated or treated with 100 ng/ml nocodazole for 12 h and 10 μM of CHK2 inhibitor for 6 h as indicated. Histogram shows the percentage of multinuclear cells. Data were compiled from three independent experiments, mean ± SD (n = 300 cells). *P < 0.05. c HELA cells transiently expressing control or Sirt1 small interfering RNA (siRNA) were treated without or with 10 μM of CHK2 inhibitor for 6 h. Cells were then incubated with nocodazole 100 ng/ml for 1 h. Mitotic markers cyclin B1 and p-H3 were measured by Western blot. See also Fig. S5