Expression of S490A acts in a dominant manner to block VEGF-induced permeability in endothelial cells14,15 and expression of this mutant in transgenic animals inhibits VEGF- or diabetes-induced retinal vascular permeability preserving visual function16 and reduces stroke induced-permeability and allows late tissue plasminogen activator treatment of stroke without hemorrhagic transformation17. The gene discussed is PLAT; the disease is stroke disorder.