Nicotinamide nucleotides are key players in the energy transforming and oxidation-reduction reactions of a cell. NADP and NADPH act as allosteric effectors in modulating enzyme activities. The reducing power of NADPH is a required cofactor for enzymes that are pro-oxidants such as nitric oxide synthase and NADPH oxidase. NADP/NADPH ratio is involved in the control of the oxidative shunt. Each of these forms has a particular role during differentiation and similarity processes as well as being target functions in the cytotoxic action of ionizing radiations and alkylating agents. The SensoLyte® NADP/NADPH Assay Kit utilizes an optimized enzymatic recycling method for the quantification of NADP/NADPH without interfering with NAD/NADH. The final product of reaction, formazan, has blue color and can be detected at absorbance 565 nm. The intensity of the color produced is proportional to NADP/NADPH concentration.