NOS2 and cancer: In addition, inducible NO synthase (iNOS, a marker of M1 phenotype) immunofluorescence staining and immunohistochemical staining of Ki‐67 of the tumor tissue on the 7th day after treatments visualized; 1) the highest expression of the M1 phenotype in the tumor tissue of the mice treated with HION‐loaded Mφs and HION‐loaded Mφs+magnet, and 2) significant suppression of Ki‐67+ (cancer cell proliferation marker; brown areas) for HION‐loaded Mφs and HION‐loaded Mφs+magnet (Figure 6f).