LRRK2 and Parkinson disease: It appears that in addition to Mn, other toxicants that activate MAPK signaling may also be influenced by LRRK2-MAPK signaling as we observed that the PD inducer MPP+ (1-methyl-4-phenylpyridinium), known to induce MAPK signaling and oxidative stress [82], increased ROS production, but inhibition of LRRK2 kinase with GSK and MLi-2 abolished MPP+-induced oxidative stress in RAW 264.7 cells (S1 Fig).