Hypoxia activates, among others, hypoxia-inducible transcription factors (HIF-1α and HIF-2α) [12,17,18], which transactivate the hypoxia-responsive element (HRE) present in the promoter of many genes encoding angiogenic, metabolic and metastatic factors [13,19,20] and contribute to the acquisition of the tumor aggressive phenotype [13,14,21]. The gene discussed is EPAS1; the disease is neoplasm.