Narrator: This is Science Today. An interaction between two proteins that may be critical to the development of Alzheimer's Disease has been discovered. Dr. Lennart Mucke, a neurology professor at the University of California, San Francisco, found a common brain molecule called amyloid precursor protein, or APP, seems to control a protein called p53, which regulates cell death.

Mucke: APP can prevent the p53 pathway from becoming activated when the cell is injured. So it could be very important, particularly for neurons, to prevent the triggering of a cell suicide process under situations of stress.

Narrator: But Mucke discovered abnormal forms of APP, which are associated with familial Alzheimer's Disease, did not stop cell death.

Mucke: So, this process might also contribute to nerve cell death in the brain during aging where neurons are going to be exposed to a number of injurious processes.

Narrator: For Science Today, I'm Larissa Branin.