CTSB and neoplasm: Currently, tumor overexpression enzymes, including cathepsin B, HDAC, and CTSL, are mainly used to develop non-natural glycans that can be converted from dormant to activated state only in tumor tissues.87,98 Considering that many of these enzymes are also present in normal cells, it may be necessary to design co-excitation devices using multiple enzymes simultaneously to improve tumor selectivity.