In in vitro assays, the Al-ProD efficiently bound to three types of albumin (HSA, BSA, MSA) and induced 30-fold strong cytotoxicity in cathepsin B-overexpressed MDA-MB231 breast cancer cells compared to cathepsin B-deficient H9C2 cardiomyocytes (Figure 3B,C). Here, CTSB is linked to breast cancer.