TGFβ, a cytokine overexpressed in the brain of AD patients [12], was shown to induce APP synthesis in vivo and in vitro and to promote Aβ formation by a transcriptional mechanism involving the signaling mother against decapentaplegic peptide 3 (Smad3) signaling pathway in astrocytes [13]. This evidence concerns the gene SMAD3 and Alzheimer disease.