In animal models of Parkinson's disease, astrocytes are also markedly altered: following dopamine neurone degeneration astrocytes become reactive, as seen by a sustained and progressive increase in the levels of the astrocyte cytoskeletal protein, glial fibrillary acidic protein (GFAP) together with changes in astrocyte morphology [10-12]. The gene discussed is GFAP; the disease is Parkinson disease.