Parameters analyzed in the study and their attribution to distinct steps of apoptosis signal transduction. Mitochondria are activated with or without involvement of caspases. Caspase-mediated mitochondrial activation may occur either by amplification of the apoptotic signal by proximal caspase activation (eg, via caspase-8 and t-Bid) or by direct mitochondrial activation through initiator caspases (eg, caspase-2). Release of cytochrome c is followed by activation of effector caspases such as caspase-3 through the formation of the apoptosome. Assessed parameters are in italics.