Consequently, ROS production was increased when miR-494 is overexpressed in neuron cells, and this effect was diminished by an introduction of PARK7 into those miR-494 overexpressed cells (Xiong et al., 2014), confirming the negative regulation of PARK7 expression by miR-494 that contributes to PD progression. This evidence concerns the gene PARK7 and Parkinson disease.