We further propose that the chemopreventive effectiveness of CystC will be potentiated by its inhibition of cathepsin B-mediated invasion and metastasis [27-30] and its inhibition of the cathepsin B-mediated activation of latent TGF-β [31-33], which co-localizes with cathepsin B to the invading face of malignant tumors [34-37]. This evidence concerns the gene CTSB and cancer.