CTSB and colorectal cancer: The researchers still think that total serum levels of cathepsin X could be a useful prognostic indicator for determining survival of patients with colorectal cancer.26 When the effect of inhibition of cathepsin X (also known as cathepsin Z) in mice was studied, the combined loss of cathepsin X and cathepsin B led to additive effects, resulting in significant and prominent delay of early and advanced tumour development.27