CTSB and cancer: The conjugation of the second mitochondria-derived activator of caspases and CTST-cleavable peptide to doxorubicin can specifically cleave to pro-apoptotic second mitochondria-derived activator of caspases and cytotoxic doxorubicin in CTSB-overexpressing cancer cells, inducing a synergy of the pro-apoptotic activity with chemotherapy 151.