Thus, immunostaining assays revealed increased global nuclear levels of HDAC2 in neurons of brain samples from postmortem human sporadic AD patients and several AD mouse models, including CK-p25, 5xFAD (expressing human APP and PSEN1 transgenes with a total of five AD-linked mutations) [115] and AβPPswe/PS-1 (also termed APP/PSEN1, expressing a chimeric mutant mouse/human APP and a mutant human PS1) [119]. Here, APP is linked to Alzheimer disease.