APP and Alzheimer disease: In control non-AD brains, Grb2 localizes all over the cell body and extends into dendrites, whereas in AD brains, the localization of Grb2 is restricted to the neuronal cell body (McShea et al., 1999; Raychaudhuri and Mukhopadhyay, 2007), where the intensity of its interaction with tyrosine-phosphorylated APP or with the C-terminal fragment (CTF) increases significantly (Russo et al., 2002; Venezia et al., 2004b) in neuronal cells and AD brains.