Bcl-2 response DN thymocyte subpopulation upon in vitro treatment with IL-7. Thymocytes from young adult mice as described for Figure 2 were treated with vehicle control (DMSO; left panel) or 3 ng/mL IL-7 (right panel) and stained for Bcl-2. Wild type (thin line), D4 Tg cells (dashed line), and C10 Tg cells (thick line) are shown with DP cells serving as a control (dotted line). Similar results were obtained from 4 independent experiments, and at doses of IL-7 from 3 to 10 ng/mL, equal effect was observed.