Parkinson's disease is one of the most common neurodegenerative disorders and still remains incurable. The condition is linked to mutations and alterations in expression in several genes, in particular that encoding alpha-synuclein. Mutations in Nurr1 leading to a reduction in expression were also found to lead to Parkinson's disease. In view of the importance of gene regulation in Parkinson's disease, we examined the effect of changes in Nurr1 expression on alpha-synuclein expression. Nurr1 was shown to be involved in the regulation of alpha-synuclein, as decreased expression of Nurr1, which has been found in Parkinson's disease patients with Nurr1 mutations, was shown to transcriptionally increase alpha-synuclein expression.