The heterodimeric complex binds to hypoxia response element (HRE) upstream of hypoxia-regulated genes, modulating expression of a variety of HIF-1 target genes, including VEGF. Increased tumor HIF-1α is correlated with increased angiogenesis, aggressive tumor growth, and poor patient prognosis, leading to the current interest in HIF-1α as a cancer drug target [9, 10]. The gene discussed is HIF1A; the disease is cancer.