Smad2 and E-cadherin were proven as miR-503-3p targets by luciferase assay, and the mRNA levels of both Smad2 and E-cadherin were lower in cancer tissues of patients compared with adjacent normal tissues, and it has been demonstrated in vitro that miR-503-3p promotes Epithelial-mesenchymal transition (EMT) and tumor metastasis by downregulation of Smad2 and E-cadherin. This evidence concerns the gene CDH1 and cancer.