Moreover, under cyclic hypoxia conditions in which the cell experiences intermittent hypoxia and normoxia environments, recent studies show HIF-2α is the dominant signaling factor for the fact that prolonged (>4–12 hr) cyclic hypoxic/normoxic cycles enhance HIF-2α but not HIF-1α accumulation among different cancer cell lines [14]. Here, EPAS1 is linked to cancer.