SMAD2 and malignant colon neoplasm: To experimentally confirm that Smad2 is a direct target of hsa-miR-140-5p, we transfected colon cancer cell lines, HCT116, RKO and SW480, with either negative control miRNA or hsa-miR-140-5p precursors, and quantified the expression of Smad2 at both protein and mRNA levels by western blot analysis and real-time qRT-PCR analysis, respectively.