PGC-1a (an alias for PPARGC1A), which regulates mitochondrial biogenesis and expression of many antioxidant genes, plays an important role in protection against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxicity (35), and expression of genes regulated by PGC-1a are reduced in substantia nigra neurons at early stages of PD (36). Here, PPARGC1A is linked to Parkinson disease.