RAB27A and Alzheimer disease: Moreover, in postmortem cholinergic basal forebrain neurons and CA1 pyramidal neurons of sporadic AD patients, several Rab proteins are upregulated, including Rab4, Rab5, Rab6, Rab7, and Rab27, indicating an overactivation of the endocytic machinery (Scheper et al., 2007; Ginsberg et al., 2010, 2011).