 The study identifies RAB12 as a negative regulator of cellular phosphorab 10 levels in mouse NIH, 3T3 cells and knockout mouse tissues through a CISPR-based genome-wide screen. RAB12 binds to a new site in the LRK2-Armedillo domain, activating LRK2 kinase for RAB phosphorylation and potentially serving as a new therapeutic target for LRK2 inhibitors that do not target the kinase domain. This article was authored by Herschel S. Dekny, Francesca Tonelli, Juan Drossan M. Esro, and others.