Tc-cell development involves 3 phases: A precursor cell that, when appropriately stimulated, can differentiate into a Tc cell An effector cell that has differentiated and can kill its appropriate target A memory cell that is quiescent (no longer stimulated) but is ready to become an effector when restimulated by the original antigen-MHC combination Fully activated Tc cells, like natural killer (NK) cells, can kill an infected target cell by inducing apoptosis.