Cathepsins are proteases involved in different step of invasiveness [78]: first, they are involved in the degradation of vascular basement membrane during angiogenesis; second, they are implicated in the dissolution of cell-cell junctions and degradation of both the epithelial basement membrane and the extracellular matrix to allow cancer cells to spread from the primary tumor mass; third, intravasation of cancer cells into the blood or lymphatic circulation, and their extravasation in distant organs require the activity of these proteases. Here, CTSS is linked to cancer.