CXCR4 and breast cancer: Moreover, pharmacological inhibition of methylation of non-invasive breast cancer cell lines (MCF-7, ZR-75-1) by using 5-Aza-2 ́-deoxycytidine increased the expression of prometastatic genes like PLAU, HPSE, C-X-C motif chemokine receptor 4 (CXCR4), and SNCG, and thereby transformed them into more invasive cells [16].