GAPDH and Alzheimer disease: For example, the expression levels of β-actin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and β-tubulin were shown to increase in some tumors [1, 2], while other conditions such as Alzheimer's disease, alcoholic hepatitis, cirrhosis, and schizophrenia have been implicated in altering the expression of endogenous reference genes and/or proteins [3, 4].