CDKN2A and familial Alzheimer disease: Wei et al. showed that the expression of cell senescence marker p16 is significantly increased in neurons, although not in astrocytes or microglia, in 5XFAD transgenic mice, which overexpress human amyloid β (A4) precursor protein 695 (APP) with three mutations detected in familial Alzheimer’s disease (FAD) and human presenilin 1 (PS1) harboring two FAD mutations [40].