APP and Alzheimer disease: Immunostaining showed that BACE1, APP, and Aβ are closely co-localized with large motor neurons in the ventral horn of the spinal cord in AD mouse models and that Aβ plaques are largely derived from the dystrophic presynaptic axonal terminals originating from glutamatergic neurons arising in the brain and projecting to spinal cord neurons (Li et al., 2013).