YY1 and Alzheimer disease: To determine whether there are differences in the expression of YY1 protein in AD brain tissue, the levels of the protein were measured by quantitative immunobloting in samples from two different regions to account for regional variability, the hippocampus and the temporal neocortex, and from two different stages of AD, labeled “moderate” (mAD) and “severe” AD (sAD), to study potential changes associated with disease severity.