CASP3 and cancer: Apoptotic stimuli activate initiator proteases such as caspase 8 and 9; these in turn activate executioner caspases, including caspase 3, which is the final link in the apoptotic signal cascade.[25,26] Although our data provide some support for activated caspase 3 as a marker of apoptotic activity in pre-cancerous tissue, the results were not entirely consistent because expression was actually higher in normal areas adjacent to cancer foci.