The transcription factor Hypoxia-Inducible Factor 1 (HIF-1) is one of the key regulators of oxygen homeostasis. It regulates the physiological responses to low oxygen levels (hypoxia) and the pathophysiology of heart attack, cancer, stroke and chronic lung disease. HIF-1 is a heterodimeric protein that consists of two subunits, HIF-1α and HIF-1β Whereas HIF-1β is constitutively expressed, the expression of HIF-1α is induced by oxygen concentrations below 6%. HIF heterodimers bind to the hypoxia response element (HRE), a 5´-RCGTG-3´ consensus sequence. Several dozen HIF-1-regulated genes have been identified so far, including genes coding for proteins involved in angiogenesis, energy metabolism, erythropoiesis, cell proliferation and viability, vascular remodeling and vasomotor responses.

