Oncogenic transformation of Nanog T cells. Mice were killed 13.5 months after irradiation and transfer of Nanog KSL cells. (A) In contrast to earlier stages after reconstitution, a significant number of GFP⁺ cells were detected in all peripheral tissues, including peripheral blood. (B) Splenomegaly and lymph node swelling were detected in all mice (n = 9). One lymph node had swollen to a huge mass. Nanog T cells infiltrate the spleen and lymph nodes diffusely leaving small islands of B cells (CD19⁺ cells). Scale bar, 100 μm. (C) Unlike during the atrophic phase, expression of β7 integrin was detected in considerable proportions of Nanog T cells in all peripheral tissue (thymus and spleen shown). Scale bar, 100 μm. (D) Southern blot analysis of the MSCV integrations present in Nanog T cells derived from 4 distinct recipients (lane 1, atrophic phase; lanes 2-4, malignant phase). DNA (5 μg) from each cell was digested with EcoRI and hybridized with a egfp probe isolated from the MSCV vector. Each band represents a separate MSCV integration. Lane 5 indicates WT thymocytes as a negative control. (E) Transformed cells in the periphery were transferred to second recipients. A diffuse infiltration of GFP⁺ cells was detected in all lymphoid tissues (thymus, peripheral blood, bone marrow, and spleen were shown in this figure) 2 weeks after transfer. Left panels show transfer of Nanog T cells at malignant phase; right panels show transfer of Nanog T cells at atrophic phase.