Multi-cellular organisms eliminate individual cells through a self-destruct process known as apoptosis. Apoptosis is critical for proper development and maintenance of tissue homeostasis. The importance of this process is highlighted by the fact that too much or too little apoptosis is the underlying cause of pathologies such as cancer, autoimmune diseases (e.g., lupus, arthritis), and neurodegenerative disorders (e.g., Parkinson's, Alzheimer's). In the early days, apoptotic cells were identified strictly by cell morphology. Now we know that biochemical signatures define a number of death...