To investigate the functional effect of HIF-1α on tumor metastasis in vivo, DiD-labeled HSC-2 cells treated with normoxia and siRNA (control group), hypoxia (hypoxia group), or siRNA-HIF-1α (siR-HIF-1α group) were intravenously injected into nude mice to establish lung metastasis. Here, HIF1A is linked to neoplasm.