MX1 and neoplasm: Notably, the increase in tumor cell-associated macrophages after 16 h depended on the presence of pFN, as we detected significantly more macrophages in direct vicinity of tumor cells in the lung tissue of pFN-competent C57BL/6-Fn(fl/fl)Mx-Cre− mice than in the lungs of pFN-deficient C57BL/6-Fn(fl/fl)Mx-Cre+ mice.