PSEN1 and Alzheimer disease: In the 3xTg-AD mice AD [269],158], hypertrophic OPCs infiltrate and accumulate around Aβ plaques [270] and in the TgAPP/PS1 mouse model, the OPCs surrounding Aβ plaques have increased Cdkn2a mRNA expression, and SA β-gal and IL-6 levels (SASP factor) reflect what is seen in the human brain.