The absence of MCP-1 in tumor stroma reduces the lung metastasis of 4T1 cells and prolongs survival.

<p>A. 1×10⁵ 4T1 cells were injected into a mammary pad of WT or MCP-1^−/− mice. The size of each primary tumor was measured and the area was calculated. <i>n = 9</i> for WT, <i>n = 8</i> for MCP-1^−/− mice. B. Primary tumors were excised from WT and MCP-1^−/− mice 31 days after tumor cell injection and weighed. <i>n = 9</i> for WT, <i>n = 8</i> for MCP-1^−/− mice. C. Mice were euthanized on day 31, and lungs were harvested and fixed in Bouin's solution. The number of metastatic tumor nodules on the surface of lungs of each mouse was counted by eye. <i>n = 9</i> for WT, <i>n = 8</i> for MCP-1^−/− mice. D. Ten thousand 4T1 cells were injected in a mammary pad of each mouse and the survival of each mouse was examined. <i>n = 8</i> for WT, <i>n = 8</i> for MCP-1^−/− mice.