A conditional KO mouse line for GPR88 in D2R-MSNs was developed in a previous study, using a A2AR-Cre driver line (A2AR-Gpr88 mice), and mutant mice showed hyperactive behavior, decreased anxiety-like behaviors and increased locomotor response to dopaminergic agonists (Meirsman et al., 2016a, 2017). The gene discussed is GPR88; the disease is Anxiety.