Exposure to either HIF-1α siRNA, HIF-2α siRNA or HIF-1α plus HIF-2α siRNA suppressed secretion of ANGPTL4 under hypoxia, showing that ANGPTL4 is a target gene of both HIF-1α and HIF-2α in osteosarcoma cells (Fig. 2e). This evidence concerns the gene HIF1A and osteosarcoma.