Assaying Drug-Induced Apoptosis

Apoptosis, frequently referred to as “programmed cell death” or “cell suicide,” is an active and physiological mode of cell death, where the cell itself prepares and executes the program of its own demise. A complex, multistep mechanism regulates the cell’s response to various stimuli by apoptosis (reviewed in refs. 1 ,2 ). The regulatory system involves the presence of at least two distinct checkpoints, one controlled by bcl-2/bax family of proteins (3 ), and another by cysteine and possibly serine proteases (4 ). There is a close association between apoptosis and regulation of cell proliferation as well as DNA repair.