Cathepsin S (CTSS) is one of a family of cathepsin proteases, which could partially alter the expression of MMP-9 in human corneal epithelial cells through protease-activated [44], MMP-9 and CTSS have synergistic effects in triple negative breast cancer (TNBC), and simultaneous deletion of both can inhibit the invasion of MDA-MB-231 human TNBC cell invasion [45]. The gene discussed is CTSS; the disease is triple-negative breast carcinoma.