Stable HIF-1α translocates to the nucleus and interacts with HIF-1β for binding to hypoxic response elements (HRE) at promoter sequences, inducing expression of genes linked to the metabolic switch and other hallmarks of cancer, such as aldolase, LDHA, PDK1, hexokinase 2 (HK2), enolase-α, VEGF, GLUT-1, survivin, and COX-2 (104, 106). Here, PTGS2 is linked to cancer.