RAB6A and Parkinson disease: A noteworthy finding is that most of the pathogenic LRRK2 mutations commonly and potently enhance its activity to phosphorylate Rab GTPases (Steger et al., 2016; Fujimoto et al., 2018; Liu et al., 2018), leading us to hypothesize that Rab hyperphosphorylation may contribute to the pathogenesis of PD.