The antileukemic activities of GADD45g are mediated through inhibition of E2F1 via the p38 MAPK–dependent signaling pathway. (A) Significantly enriched GSEA signatures in the transcriptional profile of Molm-13 cells upon GADD45g overexpression. The normalized enrichment score (NES) and P values are shown. (B) Correlation of expression between GADD45g and E2F1 in BMMNCs from AML samples (n = 56). Correlation coefficient and P value of Spearman correlation test are shown. (C) Molm-13 cells and (left) and THP-1 cells (right) with or without Dox-induced GADD45g overexpression were treated with 1 μM SB203580 for 16 hours and then subjected to western blot to detect the indicated proteins. (D) Molm-13 cells and THP-1 cells with or without Dox-induced GADD45g overexpression were treated with 1 μM SB203580 for 16 hours. Relative mRNA expression of E2F1 was quantified by qRT-PCR. Molm-13 cells with or without Dox-induced GADD45g overexpression were treated with 1 μM SB203580 (E) or transduced with lentiviral vectors expressing E2F1 (F), and the percentage of apoptosis cells was determined by fluorescence-activated cell sorting (FACS) analysis of Annexin V and 7AAD staining. Molm-13 cells with or without Dox-induced GADD45g overexpression were treated with 1 μM SB203580 (G) or transduced with lentiviral vectors expressing E2F1 (H). Representative IF micrographs (left) showing γH2AX foci from 3 independent experiments and quantification (right) of γH2AX foci (red) in nuclei (blue) per cell. Scale bar, 5 μm. Data are presented as the mean ± SD of ≥3 independent experiments, and comparisons were evaluated by using the 2-tailed Student t test. Correlations between continuous variables were calculated by using the Pearson correlation. *P < .05, **P < .01, ***P < .001, ****P < .0001. DMSO, dimethyl sulfoxide; NS, not significant.