MAPT and Alzheimer disease: Our data raise the interesting possibility that both pathognomonic lesions of AD, Aβ/amyloid-containing plaques and NFTs may independently result from impaired microglial function, specifically the ability of microglia to phagocytize and degrade or clear extracellular Aβ and tau species that are prone to aggregate and form either extracellular amyloid plaques or intracellular NFTs.