CXCR4 and breast cancer: Wound-healing assays revealed that the migration distance of MDA-MB-231 cells in the CXCR4-shRNA transfection group (0.42±0.09 mm) was significantly smaller than that in the control plasmid (2.16±0.44 mm) and the blank control (2.38±0.56 mm) groups (P<0.01), which indicated that the downregulation of the CXCR4 gene may significantly inhibit the migration of breast cancer cells.