CDKN2A and Alzheimer disease: We found that PBMCs from aMCI patients have an increase in senescence-associated beta-galactosidase (SA-β-Gal) activity, an elevated percentage of cells arrested at G0-G1 and an increased expression of interleukins 6 (IL-6) and 8 (IL-8), whereas PBMCs from AD patients showed increased p16 and p53 expression and decreased γH2AX activity, compared with healthy controls (see panels A and B of scheme in Figure 1).