CXCR4 and breast cancer: Muller et al (2001) demonstrated that CXCR4 is expressed in primary breast cancer cells and that SDF-1 was highly expressed in the most common sites of metastasis, including the lymph nodes, lungs, liver, and bone. When the CXCR4/SDF-1 interaction was blocked with a neutralising anti-CXCR4 antibody using an in vivo xenotransplant model, metastatic load was significantly reduced (Muller et al, 2001).