miR-155-5p, being the mature form of the 5’chain, inhibits the migration and invasion of lung adenocarcinoma A549 cells by targeting Smad2 (89).Furthermore, it is posited that the activation of Smad2/3 regulates the expression of target genes, including members of the zinc finger E‐box‐binding homeobox (ZEB) transcription factor family, by binding to Smad4 and translocating to the nucleus, thus contributing to lung cancer progression (90, 91). This evidence concerns the gene SMAD2 and lung adenocarcinoma.