TP53 and Alzheimer disease: Although the roles of individual E2F TFs in p53 signaling and cell-cycle dysregulation in HD are not well characterized, E2F1 dysregulation has also been implicated in neuronal death in neurodegenerative diseases such as Alzheimer’s disease [125] and Parkinson’s disease [126, 127], and was reported to be upregulated in human HD brains [115].