SERPINE2 and central nervous system cancer: Serine proteinase inhibitor clade E member 2 (SERPINE2), also known as protease nexin-1, is a member of the serine protease inhibitor superfamily and was first identified as a neurite-promoting factor for the release of cultured glioma cells [6]; various other cells such as fibroblasts, vascular smooth muscle cells, endothelial cells, platelet particles, and chondrocytes have also been reported to secrete the same [7,8,9,10].