PA is a common phospholipid that is a major constituent of cell membranes and a central intermediate for the synthesis of membrane lipids and storage lipids. Besides de novo synthesis. Cayman's Phosphatidic Acid Assay provides a fluorescence-based method for measuring PA. Lipase is used to hydrolyze PA in cellular lipids to glycerol-3-phosphate, which is then oxidized by glycerol-3-phosphate oxidase to generate H2O2. In the presence of peroxidase, H2O2 reacts with ADHP (10-acetyl-3,7-dihydroxyphenoxazine) to yield the highly fluorescent compound resorufin (excitation 530-540 nm and emission 585-595 nm).