Apoptosis, or programmed cell death, plays an essential natural
physiological role in removing cells that are superfluous, diseased, or
otherwise have served their useful purpose. During apoptosis (a term derived
from the Greek word for the falling of leaves from trees in autumn) living
cells go through a predictable, well-choreographed series of events in which
they are broken down by enzymes internally and then fall apart. The
remaining pieces are devoured by still vital neighboring cells. Apoptosis can
also be induced in cancer cells artificially, by treating tumors with drugs or
radiation. This break-through finding has led to the idea that a completely
novel way of cancer therapy might be developed using drugs that directly
switch on the cell death machinery in tumors. Certain drugs with proapoptotic
potential are now being tested for possible use in the clinic.