Caspase-3 activation is a critical determinant of genotoxic stress-induced apoptosis.

Apoptosis can be measured by number of methods by taking advantage of the morphological, biochemical, and molecular changes undergoing in a cell during this process. The best recognized biochemical hallmark of both early and late stages of apoptosis is the activation of cysteine proteases (caspases). Detection of active caspase-3 in cells and tissues is an important method for apoptosis induced by a wide variety of apoptotic signals. Most common assays for examining caspase-3 activation include immunostaining, immunoblotting for active caspase-3, colorimetric assays using fluorochrome substrates, as well as employing the fluorescein-labeled CaspaTag pan-caspase in situ detection kit.