CTSS and neoplasm: Enzymes are widely present in the tissues and organs to maintain the normal operation of human body.141 The tumor microenvironment exhibits aberrant expression of enzymes such as matrix metalloproteinases, cathepsins, phospholipases, and oxidoreductases because tumor cells grow more quickly than other normal organs and require more enzymes for functional support.142 The up or down-regulation of enzymes has attracted the attention of researchers.