NR4A2 and Parkinson disease: The nuclear retinoid X receptor (RXR) is of particular interest for therapeutic intervention due to its binding and activation of both permissive partners, NURR1 and PPARs, whose dysfunctions have been observed in AD, multiple-system atrophy, and PD [11,12,13] and that are known to regulate the expression of inflammation-associated genes [14,15].