Cathepsin B (CTSB), a ubiquitous cysteine cathepsin, is a lysosomal/endosomal protease whose participation in different pathologies such as liver fibrosis,9 atherosclerosis,10 Alzheimer disease,11 and cancer12 has been reported in the past years. This evidence concerns the gene CTSB and early-onset autosomal dominant Alzheimer disease.