Role of IL-7 in tumor induction. (A) Titration of IL-7 on Stat5b-CA x Pax5^+/− cell line (SP1). Concentrations of IL-7 were 1, 5, and 10 ng/ml. Cells were counted at each time point and graphed. Graph is representative of two independent experiments. (B) Kaplan-Meier survival analysis of Stat5b-CA x IL-7R^+/− x Pax5^+/− and Stat5b-CA x IL-7R^−/− x Pax5^+/− mice.