MMP2 and cancer: On the other hand, some cytotoxic proteins have intrinsic selectivity for cancer cells, such as Chlorotoxin (CTX), derived from the venom of the scorpion Leiurus quinquestriatus, which has been shown to bind to matrix metalloproteinase-2 (MMP-2) preferentially overexpressed on the surface of neuroectodermal origin [113] and metastatic breast [114] cancer, among others.