PTGS2 and brain neoplasm: In addition to VEGF, HIF-1α, angiopoietin 1 and 2, and basic fibroblast growth factor (bFGF), the main regulators of angiogenesis in health and in brain tumors are plasminogen activation inhibitor 1 (PAI1), nitric oxide, cyclooxygenase 2 (COX2), and thrombospondin 2 (TSP2) [181].