MAPT and Parkinson disease: Alterations in axonal transport and in the level of motor proteins have been observed in transgenic Drosophila co-expressing tau and α-synuclein, in postmortem brain tissue of sporadic PD patients, in animal and cellular models of sporadic PD and in rats overexpressing α-synuclein (Chu et al. 2012; Chaves et al. 2013; Melo et al. 2013; Roy and Jackson 2014).