DRD1 and drug-induced dyskinesia: The increase in ∆FosB associated with dyskinesia is limited to the D1R-expressing dSPN and is mediated by activation of cAMP/PKA and ERK (Andersson et al. 1999; Darmopil et al. 2009; Feyder et al. 2016; Fasano et al. 2010; Lebel et al. 2010; Schuster et al. 2008; Chen et al. 2017).