Lymphoma-free survival was extended to a much greater extent in Eμ-Myc;Rag-1-Cre;Mcl-1fl/+ mice compared with the Eμ-Myc;CD19-Cre;Mcl-1fl/+ and Eμ-Myc;CD19-Cre;Mcl-1fl/fl animals. The gene discussed is RAG1; the disease is lymphoma.