TTR and Alzheimer disease: For example, alterations in the expression of endocytotic clearance receptor, megalin [58, 64–67], subunit of the ubiquitin proteasome activator complex PA28 [40], and amyloid binding proteins such as transthyretin [58, 68], gelsolin [51], and apolipoprotein J [69], have been described in ependymal cells lining the ventricles in AD.