CTSB and Alzheimer disease: A large number of proteases that cleave tau, such as calpains [24, 61], cathepsins [41, 61, 71], caspases [28, 34, 61, 78] and the lysosomal protease Asparagine endopeptidase (AEP) [61, 77] are also cysteine proteases that are present in intracellular NFTs in AD, similar to SCRN1.