NucView® 488 Caspase-3 Substrate is a novel cell membrane-permeable fluorogenic caspase substrate designed for detecting caspase-3/7 activity within live cells in real time. Unlike conventional caspase assays, NucView® 488 Caspase-3 Substrate detects caspase-3/7 activity within individual intact cells without inhibiting caspase activity. The substrate consists of a fluorogenic DNA dye and a DEVD substrate moiety specific for caspase-3/7. The substrate, which is both non-fluorescent and nonfunctional as a DNA dye, rapidly crosses cell membranes to enter the cytoplasm, where it is cleaved by caspase-3 to form a high-affinity DNA dye that stains the nucleus bright green. Thus, the NucView® 488 Caspase-3 Substrate is bi-functional, allowing detection of intracellular caspase-3/7 activity and visualization of changes in nuclear morphology during apoptosis. The fluorescent staining produced in response to caspase-3/7 activity is compatible with subsequent fixation and permeabilization for immunostaining. NucView®488 Caspase-3 Substrate, also is available as a 1 mM solution in PBS (phosphate-buffered saline) for use in cells that are sensitive to DMSO toxicity. NucView® enzyme substrate technology is covered by U.S. patents.