In particular, the proportion of infiltrating CD45+F4/80+ cells in metastatic tumors was significantly lower in CX3CR1−/− mice than that in WT mice (31.22 ± 2.10% versus 51.79 ± 2.66% for CD45+F4/80+ cells, P<0.01; Figure 3A). This evidence concerns the gene CX3CR1 and metastatic neoplasm.