MAPT and Alzheimer disease: In mouse models of AD in which human mutant P301L tau is overexpressed in the entorhinal cortex, aggregated tau accumulates in brain regions with neuronal projections from the entorhinal cortex such as the dentate gyrus, supporting the notion that the pathological tau protein can spread from one nonadjacent anatomical region of the brain to another (4, 5, 6, 7).