We also demonstrated for the first time that MEK inhibition by selumetinib resulted in the accumulation of CD11b+ Ly6C+ MHCII+ cells within the TME of tumor-bearing mice; this is a subset of myeloid cells associated with an intermediate state in the differentiation of infiltrating monocytes into macrophages at sites of inflammation [21], or into TAMs in cancer [22–24]. This evidence concerns the gene MAP2K7 and cancer.