Consequently, this study seeks to address the role of PPARδ in MPTP toxicity by using both an in vivo MPTP mouse model of PD and an in vitro model using 1-methyl-4-phenylpyridinium iodide (MPP+), the active metabolite of MPTP, in combination with the PPARδ agonist GW0742 and the PPARδ antagonist GSK0660. The gene discussed is PPARD; the disease is Parkinson disease.