The EnzChek Caspase-3 Assay Kit #2 allows detection of apoptosis by providing a simple and reliable method for assaying caspase-3 activity. The basis for the assay is the rhodamine 110—derived substrate Z-DEVD-R110. This substrate is a nonfluorescent bisamide that is first converted by caspase-3 to the monoamide and then to the bright, green-fluorescent rhodamine 110 (excitation/emission maxima ~496/520 nm). The kit can be used to continuously measure the activity of caspase-3 and closely related proteases in cell extracts and purified enzyme preparations, using a fluorometer or fluorescence microplate reader.