ITGAM and neoplasm: To evaluate if the increase in MG Arg1 expression in larger three-week tumors (Fig 2B) was due to differentiation of circulating Gr1+ cells into MG or due to tumor microenvironmental influence on resident MG, chimeric models were generated but instead of CX3CR1GFP, CD11b-TKmt-30 mice were used as donor BM.