LGALS4 and Parkinson disease: The utilization of the UAS/GAL4 spatio-temporal expression system [20], and the availability of a plethora of promoters or enhancers of which TH-Gal4, elav-Gal4 and Ddc-Gal4 are employed in modelling PD in flies, makes Drosophila a powerful model organism [12–19].