APP and Alzheimer disease: Interestingly, Rac1 is aberrantly activated by exposure to Aβ (Manterola et al., 2013) in the brains of young AD model mice including 3-month-old APP/PS1 and 6-week-old 3xTg-AD as well as in brain and plasma samples of AD patients (Borin et al., 2018; Wu et al., 2019).