We then used Arrb1−/− and Arrb2−/− mice and microglia-specific depletion of ARRBs to demonstrate that ARRB1 ablation significantly ameliorated, whereas knockout of ARRB2 exaggerated, DA neuron degeneration, microglia activation, and neuroinflammation in two PD mouse models in vivo. The gene discussed is ARRB1; the disease is Parkinson disease.