CXCR4 and breast carcinoma: We investigated the expression level of CXCR4 in the three breast cancer cell lines, namely SK-BR-3, MDA-MB-435s and MDA-MB-231, and found that CXCR4 protein expression was down-regulated by the TPD7 in a dose-dependent manner at the concentrations used in the experiments (Fig.2A–D).