Fig 2: Post-translational and transcriptional activities of p53 in response to DNA damage. ATM: ataxia telangiectasia mutated kinase. ATR: ataxia telangiectasia and Rad3-related protein kinase. Chk1: Chek 1 kinase. Chk2: Chek 2 kinase. pH2AX: phosphorylated histone 2AX. The unnamed oval represents repair proteins that are recruited to the sites of DNA damage. The specific repair proteins that are recruited are dependent upon the type of DNA damage. The small circle indicates phosphorylation, which leads to protein activation.

Fig 3: Antidepressant-induced cell cycle profile regulation through related genes activation. GC-1 spg and GC-2 spd cells were treated with antidepressants for 48 and 96 h, the cell cycle profile (A,B,D,E) was determined and the level of p16, p21, p27, p53 proteins was controlled by Western blot technique. Representative blots are shown (C,F). Statistical differences were determined using one-way analysis of variance (ANOVA) with Dunnett’s post-hoc test; p values < 0.05 were considered statistically significant. Asterisks (*) indicate the comparison between control and antidepressants-treated cells, whereas carets (^) indicate the comparison between the same drugs in different periods (48 vs. 96). Bars indicate mean ± SD, n = 3, ***/^^^ p < 0.001, **/^^ p < 0.01, */^ p < 0.05, no indication–no statistical significance.

Fig 4: Time course for DNA damage and p53 network response in HT1080 cells following exposure to etoposide, quercetin, or methyl methanesulfonate. Representative Western blots from three separate experiments are shown. HT1080 cells were exposed to 0.1% DMSO (control cells; Ctrl), 1-µM etoposide (ETP), 30-µM quercetin (QUE), or 200-µM methyl methanesulfonate (MMS) for 3, 8, or 24 h. Total cellular protein was isolated and subjected to immunoblot analysis. GAPDH was used as an internal control.

Fig 5: Induction of (A) p-H2AX, (B) total p53, (C) p-p53(ser15), and (D–F) p53 effector proteins following 24-h etoposide, quercetin, and methyl methanesulfonate treatment. Circles, squares, and triangles represent the mean of three independent experiments (three biological replicates, each with three technical replicates). Cross bars represent the standard error of the mean (SEM). The lowest statistically significant (p < 0.05) concentrations are shown as LOELs in Table 1.