It should be noted that several receptors regulating microglial activation, such as major histocompatibility complex (MHC) class II and CD11b, which have also been observed to be up-regulated in brains of patients with PD [51,121,122], showed increased mRNA expression under basal conditions in transgenic microglia with LRRK2 R1441G mutation, thus suggesting that LRRK2 might affect the expression of these receptors. Here, LRRK2 is linked to Parkinson disease.