In the case of cathepsins, CTSB, CTSD, CTSK, CTSL, and CTSS were expressed in all breast cancer cells; however, the mRNA (Fig. 1c) and protein (Fig. 1d) expression of CTSS was much higher in the TNBC cell lines compared to the hormone-responsive cell lines. The gene discussed is CTSK; the disease is breast carcinoma.