(A–E) Quantitative RT-PCR analysis of the effect of Kras mutation status on miR-34a expression levels in MEFs (A); H358 cells overexpressing KRASWT or KRASG12C (B); H358 cells transfected with 3 KRAS siRNAs (C); SK-LU-1 cells overexpressing KRASWT or KRASG12D (D); and SK-LU-1 cells transfected with 3 KRAS siRNAs (E) (n = 3). (F and G) Quantitative RT-PCR analysis of the relative expression levels of miR-34a in whole-lung extracts from KrasLSL-G12D/+ or KrasLSL-G12D/+ p53fl/fl mice at different time points (n = 3 mice). (H) Effect of MEK and PI3K inhibition on the expression of miR-34a. MEFG12C, MEFG12C, or H358 cells were treated with DMSO, an MEK inhibitor (MEKi), a PI3K inhibitor (PI3Ki) or a combination of both inhibitors. Relative miR-34a expression levels were determined by quantitative RT-PCR (n = 3). Data are shown as the mean ± SEM. *P < 0.05, **P < 0.01, and ***P < 0.001, by 1-way ANOVA (A–H).