IHC confirmed that primary and disseminated tumor cells were of T-cell origin, based on positive staining for CD3 (Supplementary Figure 1C), and that malignant cells were immature T cells, as they were CD4+CD8+ double positive (DP), similar to lymphoma cells in Lck-MyrAkt2 mice (Supplementary Figure 1D). The gene discussed is CD8A; the disease is lymphoma.