CTSS and neuroblastoma: Western blotting, cathepsin activity assays, and proteomic analysis of lysosome‐enriched brain fractions from Tau35 mice in early (4 month) and advanced (10 month) disease stages, as well as proteolysis and endocytosis assays, cathepsin activity assays, and LysoTracker‐based live‐cell imaging in differentiated SH‐SY5Y human neuroblastoma cells, were employed to assess the effects of Tau35 fragment overexpression on protein degradation pathways.