Significantly changed proteins, some of which are associated with AD, especially related to anti-apoptosis, including ubiquitin-conjugating enzyme E2i (UBE2I), also known as ubiquitin-conjugating enzyme 9 (UBC9) [24], have been reported to participate in endogenous protection and can reduce the level of Aβ aggregates [25,26]. Here, UBE2I is linked to Alzheimer disease.