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Proc Natl Acad Sci U S A,
2003]
The most common neurodegenerative diseases are characterized by the presence of abnormal filamentous protein inclusions in nerve cells of the brain. In Alzheimer's disease, these inclusions are made of hyperphosphorylated tau protein. Together with the extracellular beta-amyloid deposits, they consitute the defining neuropathological characteristics of Alzheimer's disease. Tau inclusions, in the absence of extracellular deposits, are characteristic of progressive supranuclear palsy, corticobasal degeneration, Pick's disease, argyrophilic grain disease, and frontotemporal dementia and parkinsonism linked to chromosome 17. The identification of mutations in Tau in FTDP-17 has established that dysfunction of tau protein is central to the neurodegenerative process. At an experimental level, the expression of mutant human tau in nerve cells is leading to improved models of neurodegeneration. In this issue of PNAS, Kraemer et al. describe lines of Caenorhabditis elegans expressing transgenic wild-type and mutant human tau protein. They represent an important addition to