CDK5 and Parkinson disease: Dysregulation of Cdk5 activity has been implicated in striatal dopamine disorders that include Parkinson's disease (PD) (Chergui et al., 2004) and drug addiction (Bibb et al., 2001; Takahashi et al., 2005); however, it is not fully understood how Cdk5 interacts with dopamine signaling in the striatum.