Our Cell Meter™ assay kits are a set of tools for monitoring cell viability. There are a variety of parameters that can be used for monitoring cell viability. This particular kit is designed to monitor cell apoptosis by measuring generic caspase 3/7 activation in living cells. Caspase 3/7 activation is widely accepted as a reliable indicator for cell apoptosis. Caspases have substrate selectivity for the peptide sequence Asp-Glu-Val-Asp (DEVD). This kit uses TF2-DEVD-FMK as a fluorogenic indicator for caspase 3/7 activity. TF2-DEVD-FMK is cell permeable, nontoxic, and irreversibly binds to activated caspase 3/7 in apoptotic cells. Once bound to caspases, the green fluorescent reagent is retained within the cell. The binding event prevents the caspases from further catalysis but will not stop apoptosis from proceeding. The reagent will start to react with active caspase enzymes within 15 minutes of addition to the media. The kit provides all the essential components with an optimized assay protocol. It is used for the quantification of most activated caspase activities in apoptotic cells, or for screening caspase inhibitors. The green label allows for direct detection of activated caspases in apoptotic cells by flow cytometry.