Furthermore, i.c.v. injection of TGF-β1 alleviated N-methyl-4-phenylpyridinium ion (MPP+)-induced microglial inflammatory response and dopaminergic neuronal loss in the substantia nigra, indicating that TGF-β1 plays a role in the pathology of Parkinson’s disease (PD). The gene discussed is TGFB1; the disease is Parkinson disease.