HIF1A and neoplasm: The Warburg effect is a hallmark of cancerand indicates the process by which cancer cells use glycolysis evenin aerobic conditions, and this confers advantages for tumor growth.HIF-1α is a heterodimer of two basic helix–loop–helix/PASproteins, HIF-1α, and the aryl hydrocarbon nuclear trans-locator(ARNT).86 HIF-1α is unstable at normaloxygen levels (5–21% O2), while in low oxygen conditions(0.5–5% O2), the HIF-1α subunit becomes morestable, forms a dimer with ARNT, and moves to the cell nucleus, whereit binds to the HIF response element (HRE).