SNCA and Parkinson disease: Introducing miR-7 to an MPTP-induced neurotoxin cell culture model of PD, a commonly used PD model due to the selective effect of MPTP on dopaminergic neurons (Olanow and Tatton, 1999; Onofrj and Ghilardi, 1990), leads to downregulation of α-synuclein expression and shows a protective effect against oxidative stress (Junn et al, 2009; Li et al, 2016).