CX3CR1 and amyotrophic lateral sclerosis: The fractalkine receptor CX3CR1 plays an important role in the migration of NK cells in the CNS (Garofalo et al., 2020) as a member of the NKp protein family (Moretta et al., 2000); CXCR3+ expression was shown to be correlated with ALS progression (Murdock et al., 2021a).