Figure 1. Lymphomagenesis and pre-tumoral analysis of Eμ-myc Pin1−/− mice.

A. Lymphoma-free survival in cohorts of Eμ-myc or control mice of the indicated Pin1 genotypes. The Median survival was 108 days for Eμ-myc Pin1^+/+ (N=30), 431 days for Eμ-myc Pin1^−/− (N=23), and 108 days for Eμ-myc Pin1^+/− (N=13). P-values were calculated with the log-rank (Mantel-Cox) test: P = 0.001 for Eμ-myc Pin1^−/− vs. Eμ-myc Pin1^+/+; P = 0.002 for Eμ-myc Pin1 ^−/− vs. Eμ-myc Pin1^+/−; P = 0.7287 for Eμ-myc Pin1^+/+ vs. Eμ-myc Pin1^+/−. No lymphomas arose in non-transgenic mice, regardless of their Pin1 genotype. In B-F, six weeks old Eμ-myc pre-tumoral mice and age matched non-transgenic mice were analyzed. B. Flow cytometric analysis of circulating B cell populations. Pro/Pre B lymphocytes are defined as B220⁺IgM⁻, Immature B lymphocytes as B220⁺IgM⁺ cells. C. Numbers of circulating lymphocytes in the peripheral blood of mice of the indicated genotypes, determined with a Hematological analyzer (Beckman Coulter). D. Percentage of apoptotic cells among splenic B220⁺ lymphocytes of the indicated genotypes, as assessed by Tunel assay. E. Sections of the indicated genotypes were stained with the proliferation marker Ki67. 3-4 mice of each genotype were analyzed. Representative sections are shown. Scale bars: 100 μm. F. Cell cycle distribution of circulating B cells, analyzed as described in Supplementary Figure 1E. G. Viability of splenic B cells purified from healthy Eμ-myc or non-transgenic mice, cultured in the absence of cytokines. After 8 and 20 hours, cells were stained with Propidium Iodide (PI) to exclude dead cells. The percentage of viable PI negative cells, measured by flow cytometry is reported. H. Cell cycle entry and proliferation of purified B cells cultured in vitro in the presence of LPS, as assessed by continuous labeling with BrdU. In B-D, F, average values and standard deviations are reported, based on the numbers of samples indicated in above the bars. P-values were calculated using Student's t-test.