MRC1 and neoplasm: Then, macrophage polarization was analyzed by flow cytometry using CD206, a marker of pro-tumor/immunosuppressive macrophages.49 PLX3397 abrogated USP18 deficiency-induced reduction in pro-tumor/immunosuppressive macrophages (Figure 4C), supporting that USP18-mediated downregulation of CSF1R expression contributes to macrophage polarization.