ETS1 and cancer: Knockdown of Ets1 partially phenocopied the effects of miR-9 over-expression in gastric cancer cell lines, while restoration of Ets1 expression rescued the cancer cells from miR-9-mediated inhibition on the migration and invasion, revealing a novel post-transcriptional regulation mechanism of Ets1 by miR-9 and its clinical potentials in gastric cancer.