HIF complex formed under hypoxic conditions acts as transcriptional factor for multiple gene targets, mainly involving cell cycle regulation (e.g. MYC, p53), anaerobic metabolism (Glut 1), intracellular pH maintenance (CA9, also known as CAIX) and angiogenesis (e.g. VEGF) allowing tumour cells to quickly adapt to the hostile environment [7]. The gene discussed is CA9; the disease is neoplasm.