Apoptosis or programmed cell death (PCD) plays crucial roles in a numb
er of physiological and pathological processes. Growing evidence has s
uggested that oxidative damage, altered calcium homeostasis and abnorm
al mitochondrial functions are three key factors of PCD. Because a num
ber of studies have also indicated that a deleterious network is forme
d on the basis of the close interactions among these major apoptotic f
actors, it is proposed that the deleterious network is just the common
pathway in PCD. A variety of apoptotic stimuli can trigger the networ
k, leading to the characteristic apoptotic changes. This new theory-th
e deleterious network hypothesis of apoptosis-appears to unify some ma
jor theories of PCD, providing consistent explanations of a significan
tly larger number of the observations about apoptosis than other hypot
heses. Based on this unifying hypothesis, it is suggested that the thr
ee major factors of the deleterious network could be targeted for trea
tment of multiple apoptosis-related disorders.