Over-expression of CTSD not only stimulates tumor initiation and metastasis but also plays a crucial role in various stages of tumor progression.[5] Recent studies have found that CTSD plays an important role in multiple malignancies (such as breast cancer, prostate cancer, and gliomas) as well as inflammatory diseases, including mechanisms that encourage tumor cell growth, spread, and metastasis, while preventing apoptosis, thus contributing to disease progression.[6–8] However, the expression pattern and clinical significance of CTSD in AML remain unclear. The gene discussed is CTSD; the disease is breast carcinoma.