AD SH-SY5Y cells showed a clear increase in disulfide-linked compounds, likely including GAPDH, as the chemical origin of insoluble Aβ plaques, the formation of storage-like spots of cholesterol that trigger the production of Aβ from the β-amyloid precursor protein, and an enhanced protein phosphorylation prompting the reorganization of Tau helical filaments into Tau-paired phosphate groups. This evidence concerns the gene MAPT and Alzheimer disease.