Based on these data, we can conclude that the normal function of ARRB1 in microglia is stimulatory, whereas the normal function of ARRB2 is inhibitory, with respective to the expression of Nprl3, the activation of the STAT1 and NFκB pathways, inflammatory responses, and pathologic progression of PD (Fig. 8k). Here, NFKB1 is linked to Parkinson disease.