SMAD2 and malignant colon neoplasm: To further confirm the direct binding of hsa-miR-140-5p to the 3′-UTR of Smad2 mRNA, we cloned a 2 Kb fragment of the Smad2 3′-UTR containing 3 predicted hsa-miR-140-5p binding sites and inserted it downstream of a firefly luciferase gene in a luciferase reporter vector, which was then transfected into all three colon cancer cell lines along with hsa-miR-140-5p or negative control miRNA.