CCL2 and retinal degeneration: This is supported by the observation that all Cx3cr1 deficient lines that carry the Crb1RD8/RD8 mutation, including the Ccl2−/−/Cx3cr1−/−/Crb1RD8/RD8 and Cx3cr1−/−/Crb1RD8/RD8 mice, exhibit a more severe retinal degeneration compared to the Ccl2−/−/Crb1RD8/RD8 line of the same backcross generation and age.