Fig 6A and 6B show tumor grafts transplanted into the GCGKO mice, which formed macroscopic GFP-positive tumors. The tumors showed an organoid structure (Fig 6C), and Ki-67-positive cells were frequently identified (Fig 6D). The mass of the tumor grafts did not increase in the control mice (Fig 6E–6G), and very few, if any, Ki-67-positive cells were identified (Fig 6H). The Ki-67 labeling index of the tumors that were transplanted into the GCGKO mice was significantly higher (12±5.8%, n = 6, p = 0.013), compared with 0±0% (n = 4) for the control mice (Fig 6I). The gene discussed is MKI67; the disease is neoplasm.