LRRK2 and Parkinson disease: Rab GTPasesimplicated in vesicular trafficking have been identified as bona fide physiological substrates of LRRK2,37 but many components involved in the upstreamand downstream wiring of LRRK2 signaling pathways are yet to be discovered,and the question remains as to whether LRRK2 kinase inhibitors willhave beneficial disease-modifying effects in PD patients.