This observation aligns with previous reports of CTSD over-expression in AML[13] and solid tumors such as breast cancer and hepatocellular carcinoma.[8,14,15] Recent studies[13] have shown CTSD promotes acute myeloid leukemia progression, knocking down CTSD in leukemia cells curtails cell proliferation and antiapoptotic effects in vitro, and eases AML development in vivo, suggesting that CTSD may contribute to AML pathogenesis by promoting tumor cell proliferation, invasion, and metastasis. Here, CTSD is linked to breast cancer.