To this end, we tested whether hyperactive LRRK2 affects the axonal transport of mitochondria, a cargo that undergoes both anterograde and retrograde active transport driven by cytoplasmic dynein and kinesin-1 motors but with no known role for RAB GTPases in regulation of their motility.34 Mitochondrial transport in the axon is also of specific interest given the established role of mitochondrial dysfunction in PD pathophysiology.35 The gene discussed is RAB6A; the disease is Parkinson disease.