Fig. 1

APN level declined in aging subjects, and its deficiency correlated with immunosenescence. a-b: APN level changes in the plasma of aged male/female human individuals (n = 7–9). c-d: Bar graphs representing APN level changes in the serum and cerebral cortex of young (6-month old) and aged (15.5-month old) APN KO mice (n = 4–9). e: SA-β-gal staining and quantification in the brain of aged mice (n = 5–6). f: Representative immunoblots and bar graphs showing expression of p16 and p21 in the cortex of aged mice (n = 5). g-h: Bar graphs showing dopamine and serotonin levels in the cortex of aged mice (n = 9–10). i-j: mRNA level of Baz2b and EHMT1 in the cortex of aged mice (n = 4–5). Data expressed as mean ± SEM, *p < 0.05, **p < 0.01, ***p < 0.001