POU5F1 and neoplasm: Hypoxia in the tumor microenvironment induces stable expression of hypoxia-inducible factors (HIF), which promotes angiogenesis via VEGF induction (23, 25), stimulates pluripotency by increased expression of pluripotent markers (OCT4, SOX2, NANOG) (25, 26), and increases acidosis through enhanced expression of carbonic anhydrase IX (CA-IX) (27).