The activation of caspases is a final commitment step for apoptosis. It is now evident that signal transduction pathways involving specific protein kinases modulate the apoptotic response. Both pro-apoptotic and anti-apoptotic pathways integrate environmental cues that control the decision to undergo apoptosis. Pro- and anti-apoptotic signal pathways regulate the activation of the caspases. In this review we describe our current understanding of apoptotic signal transduction.