Among the 500–600 proteases identified in mouse and human, the cathepsin (Cts) family includes proteases that orchestrate numerous critical physiological processes and are involved in many different diseases such as neurological disorders, cardiovascular diseases, arthritis, obesity, and cancer.25,26 Cysteine Cts proteases, which comprise 11 members in humans (Cts B, C, F, H, K, L, O, S, V/L2, X, and W), belong to the papain-like cysteine protease family. This evidence concerns the gene CTSB and cancer.