CA9 and hemangioblastoma: Subsequently, HIF-VEGF-VEGFR2, HIF-EPO, HIF-CAIX, HIF-SDF1β-CXCR4, HIF-EphB4/EphrinB2, and HIF-Notch/Dll4 are thought to play critical roles in angiogenesis in hemangioblastoma (5 ,9, 21–25).