Emerging evidence suggests the crucial role of fractalkine in neuron-to-glia communication signalling in PD29, and SDF-1 is correlated with the apoptosis of PD-related neurons by activating chemokine receptor 4 (CXCR4)30.In contrast to our findings, previous studies have reported that peripheral RANTES is significantly elevated and suggested that CCL5 produced from the CNS penetrates into the serum through the BBB31. The gene discussed is CCL5; the disease is Parkinson disease.