A) Kaplan-Meier curve of lethally irradiated mice reconstituted with Trib2+/+ or Trib2-/- cells expressing intracellular Notch1 (ICN; “***”, p = 0.0002). Mice with a body condition score of ≤2 and decreased mobility were euthanized (n = 8 Trib2+/+ and n = 12 Trib2-/- recipients. B) Flow cytometry was used to assess the immunophenotype of leukemic cells in the spleen. C) Spleen weights and D) WBC of moribund mice are shown. E) Representative H&E staining of spleens harvested from moribund mice (left panels, 10X magnification, scale bar = 50μM; right panels, 100X magnification, scale bar = 10μM). F) Kaplan-Meier curve of lethally irradiated mice reconstituted with Trib2+/+ or Trib2-/- cells expressing the weakly oncogenic Notch mutant, Notch 1 L1601PΔP (“****”, p<0.0001), (n = 16 Trib2+/+ and n = 7 Trib2-/- recipients). G) Flow cytometry was used to assess the immunophenotype of leukemic cells in the spleen. H) Spleen weights and I) WBC of moribund mice are shown (“*”, p = 0.013). J) H&E staining of spleens from moribund mice (left panels, 10X magnification, scale bar = 50μM; right panels, 100X magnification, scale bar = 10μM).