Caspases play important roles in apoptosis and cell signaling. The activation of caspase-3 (CPP32/apopain) is important for the initiation of apoptosis. Caspase 3 is also identified as a drug-screening target. Caspase 3 has substrate selectivity for the peptide sequence Asp-Glu-Val-Asp (DEVD). This Amplite® Caspase-3 Assay Kit uses Z-DEVD-ProRed™ as the fluorogenic indicator for assaying caspase-3 activity. Cleavage of R110 peptides by caspases generates strongly red fluorescent ProRed™ that can be monitored fluorimetrically at ~620 nm with excitation of ~530 nm. Z-DEVD-ProRed™ is recognized as the most sensitive red fluorogenic caspase 3/7 substrate. This kit can be used to continuously measure the activities of caspase-3 in cell extracts and purified enzyme preparations using a fluorescence microplate reader or fluorometer. It can also be used with flow cytometry for analyzing cell apoptosis and the activities of caspases 3 and 7.