(A) Cells were transfected with pCMV, pCMV-miR-340 plasmids or not transfected (control); 48 h after transfection, protein samples were used to perform western blot analysis. The downstream targets of MAPK pathway total ERK, p-ERK, total p38, p-p38, total JNK 1/2, p-JNK 1/2, was analyzed. β-Actin was used as a loading control. (B, C) The relative protein expressions of the control, pCMV and pCMV-miR-340 transfected HCT-116 and DLD-1 colon cancer cells were compared and represented as graph. (D) The sensitization of miR-340 treated HCT-116 and DLD-1 colon cancer cells to 5-FU was analyzed by cell proliferation MTS assay. HCT-116 and DLD-1 colon cancer cells were transfected with pCMV and pCMV-miR-340 plasmids followed by 5-FU treatment at concentration of 15μg/ml and incubated for 48 h. The cell viability in pCMV-miR-340 and 5-FU treated cells was compared to pCMV and 5-FU treated cells. The data are presented as means with SDs for three independent experiments. *p<0.05; **p<0.01; ***p<0.001.