Of all the cellular processes that must be tightly regulated, death is one of the most important: too little cell death and the result can be uncontrolled growth; too much, however, and degeneration or developmental defects ensue. But it is not simply a matter of life or death. The complex interplay between the components of different death pathways — coupled with the other mechanisms that feed into these pathways to promote or prevent apoptosis — mean that the decision to survive or die can be made at a number of points.

Some of these crucial decision points are the subject of this month's Focus on apoptosis. On page 401, Guy Salvesen and Colin Duckett review the inhibitor of apoptosis (IAP) proteins, which are key regulators that control cell-death pathways by regulating the main executioner enzymes — caspases. However, more recent evidence has implicated the IAP proteins in other cellular functions, some of which are not necessarily linked to apoptosis. Some of the latest findings in this area are highlighted on page 398, where the relationship between IAP proteins and Drosophila Reaper, Hid, Grim and Sickle is discussed.

The key players in apoptosis have been studied in many organisms — from flies and worms to mammals. Yeast, on the other hand, lack much of the molecular machinery that is responsible for apoptosis in more complex, multicellular organisms. But, as Can Jin and John Reed discuss in an Opinion article on page 453, the expression of certain animal apoptosis proteins in either budding or fission yeast yields informative and useful phenotypes. In this way, yeast can provide a powerful resource in the discovery of novel genes — and chemical compounds — that modulate the cell-death pathways of humans and other higher organisms.