Injury to the cornea leads to formation of mediators that initiate and amplify inflammatory responses and neovascularization. Among these are lipid mediators generated by a cytochrome P450 (CYP) enzyme identified as CYP4B1. Increased corneal CYP4B1 expression increases limbal angiogenic activity through the production of 12-hydroxyeicosatrienoic acid (12-HETrE), a potent inflammatory and angiogenic eicosanoid. We used siRNA duplexes targeting CYP4B1 to substantiate the link between CYP4B1 expression, 12-HETrE production and angiogenesis in a model of suture-induced corneal neovascularization. Intrastromal sutures induced a time-dependent neovascular response which was significantly attenuated by CYP4B1-specific siRNAs but not by nonspecific siRNA. CYP4B1 mRNA was reduced by 60% and 12-HETrE's levels were barely detected in corneal homogenates from eyes treated with the CYP4B1-specific siRNA. The decreased neovascular response in CYP4B1 siRNA-treated eyes was associated with a 75% reduction in corneal VEGF mRNA levels. Transfection of rabbit corneal epithelial cells with CYP4B1 cDNA induced VEGF expression. Conversely, treatment with CYP4B1 siRNA or addition of a CYP4B1 inhibitor significantly decreased VEGF mRNA levels; addition of 12-HETrE potently increased them. The results strongly implicate the corneal CYP4B1 as a component of the inflammatory and neovascular cascade initiated by injury and further suggest that CYP4B1-12-HETrE is a proximal regulator of VEGF expression.