Recent studies have revealed elevated levels of proteins associated with aging, such as cell cycle repressors (p16, p53, and p21), in various cell types, including astrocytes, microglia, and neurons in the brains of AD patients (Baker et al. 2018; Pekny et al. 2016; Turnquist et al. 2016; McShea et al. 1997). Here, CDKN2A is linked to Alzheimer disease.