CDKN2A and Insulin resistance: Specifically, mice that developed spontaneous peripheral insulin resistance at either young (3-months-old) or old (24-months-old) age also displayed signs of brain insulin resistance (i.e., elevated insulin in the CSF, elevated pIRS1 (Ser307 and Ser612)], and senescence (i.e., neurite loss, elevated Cdkn1a and Cdkn2a and SA β-gal activity).