HIF1A and neoplasm: Angiogenesis, new blood vessels developed from preexisting vessels within a living organism, is crucial during tumorigenesis and tumor progression.8 This process is exceedingly regulated by vascular endothelial growth factor (VEGF), the principal proangiogenic factor which gene expression is transcriptionally activated by HIF-1α.9-11 Whereas under the HIF-1α gene silencing condition, angiogenesis in osteosarcoma remains elusive.