Figure 1.

Kaplan–Meier analysis of tumor incidence studies. Thymic lymphoma-free survival is plotted versus time in months for Rag2^−/−Atm^−/− mice and littermate controls. A drop in the curve represents the sacrifice or death of an animal diagnosed at necropsy with malignant thymic lymphoma. Tick marks represent the sacrifice or death of an animal that was not subsequently diagnosed with malignant thymic lymphoma. For purposes of statistical analysis Rag2^−/−Atm^+/+ and Rag2^−/−Atm^+/− mice were considered as one group denoted Rag2^−/−Atm⁺ (n = 17); likewise, Rag2⁺Atm^+/+ and Rag2⁺Atm^+/− were considered as one group denoted Rag2⁺Atm⁺ (n = 13). As no animals from either of these groups were diagnosed with malignant thymic lymphomas, the curves for these two groups are at 100% event-free survival. To distinguish between Rag2^−/−Atm⁺ and Rag2⁺Atm⁺ mice, dots above the tick marks were used to indicate the death of Rag2^−/−Atm⁺ mice.