PROK2 and central nervous system cancer: In this regard, our demonstration that PKRA7 is capable of penetrating the blood-brain barrier in the mouse and acts to inhibit intracranial xenograft tumor formation by glioma cells presents an alternative strategy to inhibit tumor angiogenesis via a mechanism distinct from that of anti-VEGF since PK2 enhances angiogenesis through its G-protein coupled receptor activated pathways [7].