DRD1 and infection: Next, FLEX-shFyn was packaged into a lentivirus (Ltv-FLEX-shFyn) and the efficacy of in vivo infection in D1R DMS neurons was evaluated by using Drd1-Cre-Ai14 mice which express Cre recombinase and the red fluorescence protein, tdTomato specifically in D1R neurons (Shuen et al., 2008).