Knockdown of PADI4 in A549 lung cancer cells resulted in a striking reduction in the EMT-associated Snail Family Transcriptional Repressor 1 (Snail1/mothers) against the decapentaplegic homolog 3⁄4 transcriptional complex, which was consistent with alterations in migratory and invasive phenotypes of A549 lung cancer cells. This evidence concerns the gene SNAI1 and lung cancer.