SPB3 is a putative cysteine protease inhibitor, and other members of the serpin family have been associated with Aβ accumulation in AD brain.[58] AATM, classically known as a liver enzyme, has also been reported to be increased in the CSF of Alzheimer's patients.[59] To our knowledge, however, this is the first report of increased levels of these proteins in excitatory human AD neurons and therefore may point to pathogenic pathways in these neurons. Here, CTSB is linked to Alzheimer disease.