Moreover, hypoxia also enhanced the migratory ability and tube formation capacity of HUVECs, which showed to be reversed by the incubation with the conditioned medium derived from mPRα knocked-down A549 cells; these findings indicate that mPRα knockdown could reduce HIF1α-induced VEGF secretion into tumor microenvironment, therefore impairing hypoxia-induced angiogenesis in HUVECs. This evidence concerns the gene HIF1A and neoplasm.