Notch1 and its direct target genes are up-regulated in T-lymphomas from ZMYM2-FGFR1–transduced mice. (A) The immunophenotype of lymphocytes from the diseased mice shows that the majority are CD4⁺CD8⁺ with high CD25 expression. Relatively few cells expressed cell-surface TCRα, TCRβ, or CD3. (B) Heat map (left panel) showing up-regulation (P < .05) of transcript levels of Notch1 and its direct target genes in sorted LSCs (GFP⁺Lin-Sca-1⁺c-kit⁺) compared with sorted normal HSCs (Lin-Sca-1⁺c-kit⁺) and Thy1⁺ DP thymocytes (Thy DP) from normal Balb/c mice. GSEA (right panel) showed that most Notch1 direct target genes are highly up-regulated in T-lymphoma (for further details, see the supplemental Methods). (C) Semiquantitative RT-PCR analysis of Notch1 and its direct target genes in sorted, normal DP thymocytes (Thy DP), unsorted normal Balb/c mesenteric lymph node cells (LN), and lymphomas from individual diseased founders (T-lym) and ZNF112 cells, confirms the microarray observations. (D) Real-time RT-PCR confirmation of up-regulation of several well-characterized Notch1 target genes. (E) Western blot analysis showing that the protein levels of both activated Notch1 (intracellular domain) and its downstream target genes, Ptera and Myc, are significantly increased in T-cell lymphoma (T-lym) compared with cells from normal Balb/c mesenteric lymph nodes (MLN).