{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Hypoxia-inducible factor 1-alpha, also known as HIF-1-alpha, is a protein that in humans is encoded by the HIF1A gene. Two alternative transcripts encoding different isoforms have been identified, the alpha and beta subunits. HIF-1 plays an essential role in cellular and systemic responses to hypoxia."}]},{"type":"paragraph","children":[{"type":"text","value":"HIF-1 is a critical mediator of the hypoxic response that upregulates expression of proteins that promote angiogenesis, anaerobic metabolism, and many other survival pathways. HIF-1alpha is expressed in many types of tumors. The expression of HIF-1alpha is correlated with tumor angiogenesis, cancer progression and clinical outcome in various solid tumors including breast cancer, type 1 endometrial carcinoma, sarcoma, head and neck tumor and brain tumor. Importantly, hypoxia has been clinically demonstrated to predict an adverse treatment outcome in the radiotherapeutic management of cancer of the head and neck, uterine cervix and soft tissue sarcomas. HIF-1 alpha may be of value in analyzing the cancer cell response to therapy."}]}]}