The human body is constantly shedding old or damaged cells, so that new cells may take their place. This natural process of cellular self-destruction (called “apoptosis” from an ancient Greek word meaning “falling off”) is hard-wired into cells.

How does a cell kill itself?

If cells are no longer needed, they commit suicide by activating an intracellular death program. This process is therefore called programmed cell death, although it is more commonly called apoptosis (from a Greek word meaning “falling off,” as leaves from a tree).

Why does apoptosis happen?

Apoptosis occurs normally during development and aging and as a homeostatic mechanism to maintain cell populations in tissues. Apoptosis also occurs as a defense mechanism such as in immune reactions or when cells are damaged by disease or noxious agents (Norbury and Hickson, 2001).