Constitutively active Notch-IC drives RT. (A) Pairwise Kaplan-Meier overall survival analysis for Cd19-Cre^Notch1-IC (yellow) vs Eµ-TCL1^Notch1-IC(orange) mice; for comparison included from Figure 2 were Cd19-Cre (black), Cd19-Cre^Akt-C (gray), Eµ-TCL1 (blue), and Eµ-TCL1^Akt-C (red) mice. (B) Representative images of spleens from Cd19-Cre^Notch1-IC vs Eµ-TCL1^Notch1-IC mice aged 10 to 12 months. (C) Box plot of spleen weight for mice aged 10 to 12 months. (D) Representative hematoxylin and eosin staining of spleen preparations derived from Eµ-TCL1^Notch1-IC mice showing DLBCL-like morphology. (E) Relative mean cell size (FSC) of Cd5⁺ splenic B cells aged 10 to 12 months. (F) Box plot showing pAkt (Ser473)/panAKT quantified from immunoblot of supplemental Figure 7D. (G) Box plot showing Dll1 protein level of Cd4⁺ T cells from Eµ-TCL1^Notch1-IC mice. (H) Graphical abstract displaying Notch1 functional role in RT. **P ≤ .01, ***P ≤ .001 (unpaired, 2-sided Student t test).