Rab4a  Neumann-Pick disease Alzheimer's Disease Down's syndrome  Reduced Rab4-dependent recycling in vitro in Neumann-Pick type A and type C fibroblasts. Postmortem samples: increased Rab4 in patients with AD and mild cognitive disorder Aβ partially co-localizes with Rab4 in a mouse model of Down Syndrome  Cataldo et al., 2000; Choudhury et al., 2004; Arriagada et al., 2010; Ginsberg et al., 2010