The nuclear receptor-related-1 protein (Nurr1, also known as NR4A2), a member of the inducible orphan nuclear receptor family (Wang et al., 2003), is critical for the development and survival of midbrain DA neurons, which are predominantly affected and progressively degenerate in PD (Saucedo-Cardenas et al., 1998; Le et al., 1999; Jiang et al., 2005; Smidt and Burbach, 2007). Here, NR4A2 is linked to Parkinson disease.