Deletion of CX3CR1 aggravates microglial neurotoxicity in response to LPS in the MPTP model of PD and in the superoxide dismutase 1 (SOD1) G93A model of ALS [57], suggesting that CX3CL1 signaling may limit microglial toxicity [57]. Here, CX3CR1 is linked to amyotrophic lateral sclerosis.