HIF1A and metastatic neoplasm: <i>In vivo</i> studies indicated that compared with using DS or HIF-1α knockdown alone, DS with HIF-1α knockdown can better suppress the volume and number of metastatic tumors, and reduce the mRNA and protein expressions of HIF-1α, MMP-2, TGF-β, Twist and N-cad in metastatic tumor tissues of nude mice.