CX3CL1 and Alzheimer disease: Bolos et al. (2017) reported that CX3CR1 deficiency decreases the internalization of 2N4R tau monomer in microglia both in vitro and in vivo. They proved that phosphorylation of tau at S396, which is strongly implicated in AD-associated tau pathology, reduces its affinity for CX3CR1 using affinity chromatography technology. Both phosphorylated tau at S396 levels and CX3CL1 expression are increased in advanced Braak stages of AD, raising a possibility that CX3CL1 may inhibits tau clearance by microglia through competing with tau for binding to CX3CR1 (Bolos et al., 2016).