Indeed, we observed that HIF-1 target genes ANGPTL4, VEGFA, GLUT1, PGK1 and HK2 were down-regulated at mRNA level when DEC2 is knocked down in several osteosarcoma cell lines, while the mRNA level of HIF-1α showed no obvious change by the DEC2 knockdown. This evidence concerns the gene HK2 and osteosarcoma.