We and others previously reported that knock-in mice expressing the pathogenic hyperactive Lrrk2G2019S mutation, exhibit deficits in dopamine release within the striatum. To investigate the underlying molecular mechanisms, we conducted quantitative phosphoproteomic Liquid Chromatography-Mass Spectrometry (LC-MS) studies on striatal synaptosomes from Lrrk2G2019S mice. Mice were treated with vehicle control or the potent and specific LRRK2 kinase inhibitor MLi-2, as pharmacological inhibition of the hyperactive Lrrk2G2019S kinase increases the likelihood of identifying in vivo changes in phosphoregulation.