Detailed molecular analyses in mice and cells led to the findings that in Alzheimer’s disease Pin1 regulates amyloid precursor protein (APP) processing and amyloid-beta production (Pastorino et al., 2006) while it is required for Tau dephosphorylation and correct neurofibrillary organization (Liou et al., 2003). Here, PIN1 is linked to early-onset autosomal dominant Alzheimer disease.