One way to regulate programmed cell death (apoptosis) is to keep the various components of apoptotic pathways in separate locations, and allow them to come into contact only when needed. The two main stores are the mitochondria and the plasma membrane, but a third has now been identified – the endoplasmic reticulum. Moreover, there is evidence that the protein stored here, caspase-12, is involved in the neurodegeneration associated with Alzheimer's disease.