Mcl-1 synergizes with Myc in lymphomagenesis. (A) Kaplan-Meier plot of tumor-related deaths in Eμ-Myc/Mcl-1(33) mice (red, n = 6), median survival, 30.5 days and Eμ-Myc transgenic mice (black, n = 34), median survival, 94 days. Survival curves are significantly different (P < .0001). (B) Dot plot showing immunophenotype of a representative B-cell tumor from an Eμ-Myc/Mcl-1(33) mouse. (C) Graph of percentage pre-B cells (B220⁺ CD19⁺ IgM⁻ IgD⁻) in E18 blood; genotypes as indicated. Blood was isolated from the jugular vein of E18 embryos and red cells depleted before staining with cell surface markers for flow cytometry. **P<.01 ; ***P<.001. (D) Dot plot examples of E18 white blood cell analysis. Numbers at bottom of quadrants indicate mean percentage pre-B cells (B220⁺ CD19⁺ IgM⁻ IgD⁻) ± SEM (n = 8 WT; 3 VavP-Mcl-1(33); 17 Eμ-Myc; 11 VavP-Mcl-1/Eμ-Myc). (E) Kaplan-Meier plot of tumor-related deaths for lethally irradiated C57BL/6J mice reconstituted with 2 × 10⁶ fetal liver cells (1-3 recipients per fetal liver) from Eμ-Myc/Mcl-1(33) mice (red, n = 5), 12 recipients, median survival, 41 days and Eμ-Myc mice (black, n = 7), 16 recipients. Survival curves are significantly different (P < .0001). (F) Dot plot showing immunophenotype of a representative stem/progenitor cell tumor arising after transplantation of Eμ-Myc/Mcl-1(33) fetal liver cells.