Alzheimer's disease (AD), a neurodegenerative disorder that severely impairs cognitive and memory function in elderly people, is partially characterized neuropathologically by extracellular deposits of beta-amyloid protein. We were interested in studying how beta-amyloid may be involved in aspects of AD pathogenesis. To do this, we expressed the last 100 amino acids of the amyloid precursor protein, which contains the entire beta-amyloid region, in PC12 cells and in brains of transgenic mice. We found that expression of this fragment of beta PP altered cytoskeletal changes in PC12 cells following nerve growth factor treatment. Using both in vitro and in vivo systems of human beta PP expression, we can study the biology of beta PP and test hypotheses of how it may be involved in Alzheimer's disease.