These results indicate that the Mre11 mutation suppresses pro-B-cell lymphomas in a context where pro-B-cell lymphomas normally arise in the majority of mice by 8–10 weeks of age in spite of the preserved ability of p53 null Mre11 null and p53 null Mre11H129N/− to generate oncogenic chromosomal translocations (including IgH: Myc translocations) and also chromosomal translocations outside of the IgH locus, not only in B cells but also in nonlymphoid cells. The gene discussed is MRE11; the disease is B-cell non-Hodgkin lymphoma.