After transfecting miR-20a-5p mimics and anti-miR-20a-5p mimics into HT29 and HCT116 cell line respectively, we found miR-20a-5p mimics inhibited Smad4 3′-UTR luciferase activity in HT29 cells, conversely, anti-miR-20a-5p mimics promoted Smad4 3′-UTR luciferase activity in HCT116 cells (Figure 1F, P < 0.05), which demonstrated that miR-20a-5p might directly target the 3′-UTR of Smad4 in CRC cell lines. This evidence concerns the gene SMAD4 and colorectal carcinoma.