CTSZ (Cathepsin Z), also known as Cathepsin X and Cathepsin P, is 303 amino acid protein. It is lysosomal cysteine proteinase and member of the peptidase C1 family. It exhibits carboxy-monopeptidase as well as carboxy-dipeptidase activity. This gene is widely expressed in cancer cell lines, primary tumors. CTSZ may be involved in tumor progression. And, CTSZ plays a role in normal intracellular protein degradation