<p>The effect of <i>let-7b</i> mimic, paclitaxel or gemcitabine on the phosphorylation of MEK, ERK1/2, and AKT in <i>KRAS</i> mutant A549 (A) and Panc-1 cells (B). The apoptotic cells were detected by flow cytometry using Annexin V-FITC and PI dual staining, and the apoptotic protein markers caspase-3, PARP and BCL-2 were assessed by Western blotting in A549 (C) and Panc-1 cells (D). Each experiment was carried out at least 3 times.</p