HIF1A and neoplasm: HIF-1 is a critical transcription factor in various cellular and physiologic processes, as it can facilitate adaption of tumor cells to hypoxia by activating the transcription of downstream target genes and regulating multiple aspects of tumorigenesis, including cell proliferation, survival, differentiation, apoptosis, angiogenesis, immunosurveillance, metabolism, metastasis, as well as radiation response [37–39].