Secreted alkaline phosphatase (SEAP) is widely used as reporter gene to analyze the activity of promoters and transcriptional factors and to tract gene expression in cell culture or animals. SEAP can be effectively secreted into culture medium and serum. This unique characteristic of SEAP makes it convenient to kinetically analyze gene expression over a period of time using a single culture or animal. SensoLyte® pNPP Secreted Alkaline Phosphatase Reporter Gene Assay Kit provides a sensitive colorimetric assay of placental alkaline phosphatase for both secreted and membrane-bound forms of placental alkaline phosphatase. The kit contains: pNPP chromogenic substrate (absorption maximum = 405 nm upon dephosphorylation), Assay buffer, Stop solution, A “mix and read” assay protocol that is compatible with high throughput screening liquid handling instruments.