Expression of MAPK8IP1 (mitogen-activated protein kinase 8 interacting protein 1), a key regulatory protein that opposes MAPK8-mediated activation of downstream transcription factors and colocalizes with amyloid deposits in the neurofibrillary tangles of Alzheimer's disease patients (33), is significantly diminished in Def-Ts. This evidence concerns the gene MAPK8IP1 and early-onset autosomal dominant Alzheimer disease.