ANCIENT MOLECULAR MACHINERY. “Cells monitor their environment and continuously make decisions as to whether they should continue living. When faced with a potential apoptotic signal the cell wants to avoid triggering premature or unneeded apoptosis all the while it wants to make sure to initiate apoptosis if the signal is of significant intensity. This is achieved by balancing pro- and anti-apoptotic machineries.”
http://www.sciencedirect.com/science/article/pii/S0167488910002764