APP and Alzheimer disease: Recently, there has been growing evidence suggesting that Rac1 activity is aberrantly elevated in AD patients and various AD animal models, such as APP/PS1 mice, ApoE-/-mice, 3xTg-AD mice, AlCl3 and D-gal co-induced AD rat, and human Aβ42 transgenic fly [25,155,177,178,179,180,181,182,183,184].