CXCR4 and breast cancer: CXCR4 expression has been well studied in a different hematological and non- hematological malignancies e.g. chronic lymphocytic leukemia, myelodysplastic syndrome, multiple myeloma, pediatric AML, lung cancer, ovarian cancer, and breast cancer, in which it has been associated with adverse clinical outcomes, invasion, chemotherapy resistance, and metastasis (Cao et al., 2019).