Experimental evidence indicates that the inflammatory response induced by α-synuclein is mediated by TLR4 (18), and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD pathology is less severe in TLR4 knockout mice than in wild-type mice (15). The gene discussed is TLR4; the disease is Parkinson disease.