APOE and Alzheimer disease: When studying mice that were carrying both genes of familial (3xTg) and sporadic (ApoE4) AD, hippocampal histology showed that female ApoE4/3xTg mice had elevated levels of Aβ proteins, β-site APP cleavage enzyme (BACE1), and Sp1 (BACE1 transcription factor) in comparison to male ApoE4/3xTg, female 3xTg, and nonTg mice [157].