Chemical. CAS 2616-72-0. Formula C18H15CINO5P. MW BD9837. Naphthol AS-TR Phosphate is a fluorogenic substrate for acid and alkaline phosphatases. Naphthol AS-TR Phosphate is converted to naphthol AS-TR displaying excitation/emission spectra of 388/512nm. The fluorescence is a quantitative marker of acid and alkaline phosphatase activity. Acid and alkaline phosphatases are often used as clinical markers of disease, since the concentration of human acid and alkaline phosphatases undergo pronounced changes in particular diseases, resulting in unusually high or low concentrations. It is a histochemical substrate commonly used in conjunction with diazonium salts to form a specific azo dye for immunohistology applications. Naphthol AS-TR Phosphate is a cyclic-AMP response element-binding protein CREB-CREB binding protein CBP transcription factor complex inhibitor and a potential therapeutic agent for lung cancer.