Caspases play important roles in apoptosis and inflammation. Caspase Assay Kit (orange, VAD-FMK) (ab270770) is used by researchers seeking to quantitate apoptosis via caspase activity in cultured cells and tissues.

The FLICA reagent SR-VAD-FMK enters each cell and irreversibly binds to activated caspases. Because the SR-VAD-FMK FLICA reagent becomes covalently coupled to the active enzymes, it is retained within the cell, while any unbound SR-VAD-FMK FLICA reagent diffuses out of the cell and is washed away. The remaining red fluorescent signal is a direct measure of the active caspase enzyme activity present in the cell at the time the reagent was added. Cells that contain the bound FLICA can be analyzed by a fluorescence plate reader, fluorescence microscopy or flow cytometry. Cells labeled with the FLICA reagent may be read immediately or preserved for 16 hours using the fixative included in the kit. Unfixed samples may also be analyzed with Hoechst 33342 to detect changes in nuclear morphology.