ARRB1 and Parkinson disease: The expression of β-repressor protein 1 (ARRB1) and β-repressor protein 2 (ARRB2) in microglia is reciprocally regulated, and Fang found that ARRB1 ablation ameliorated the pathological features of PD, whereas ARRB2 knockout aggravated the pathological features of PD (Fang et al., 2021).