Cellular signaling pathways and cytoskeletal organization.

We describe a possible mechanism by which the amyloid precursor protein (APP) may be linked to the intraneuronal pathology of Alzheimer's disease (AD). Extracellular proteolytic products of APP may directly or indirectly transduce signals to cells under normal as well as pathological conditions. This activity appears to reside in the cysteine-rich amino terminus of APP. How APP or its metabolic products may affect the phosphorylation of tau is considered.