Figure 1.

Rag-1 is required for thymic lymphoma development in Atm^−/− mice. Tumor-free survival of mice is plotted with time. Each data point represents the sacrifice or death of a terminally ill mouse. A drop in percentage reflects the sacrifice or death of a mouse with thymoma. As with Atm^−/− mice (□; n = 8), 100% of the Atm^−/−Rag-1^+/− mice (⋄; n = 5) developed thymic lymphoma. The mean survival time was 4.8 months for Atm^−/− mice and 4.7 months for Atm^−/−Rag-1^+/− mice. All Atm^−/−Rag-1^−/− mice (○; n = 9) died or were sacrificed with no overt thymic lymphoma or other tumors. The mean survival time was 9 months, comparable to Rag-1^−/− mice housed under the same conditions. Three of the nine Atm^−/−Rag-1^−/− mice died of pneumonia at 5–6 months with no sign of thymic lymphoma. Mouse food containing antibiotics was used to treat one Atm^−/−Rag-1^−/− mouse of this data set with similar symptoms.