EPO and neoplasm: On the other hand, in OSCC, tumor progression and metastasis are also sustained by the presence of hypoxia-inducible factor (HIF) and related genes induced by hypoxia, such as VEGF, interleukin 1A (IL-1A), endothelin 1, platelet-derived growth factor B (PDGFB) and erythropoietin (EPO) [23].