CXCR4 and neoplasm: In Figure 5, we measured the cytotoxicity of 4T1 tumor cells by B cells in the presence of anti-FasL and the CXCR4-specific inhibitor AMD3100, and found that both Fas/FasL and CXCR4/CXCL12 pathways are involved in B cell-mediated killing of tumor cells.