MRC1 and neoplasm: In contrast, 131I-hu4G4 tended to reduce the abundance of M2 microglia, as the ratio of F4/80+ CD206+ cells in tumor tissues was significantly lower after 131I-hu4G4 treatment (12.18 ± 2.11 %) than after PBS treatment (28.27 ± 7.689 %) (Figure 5F).