Myc-induced leukemias undergo apoptosis following irradiation, whereas Myc-induced leukemias that overexpress EGFP-bcl-2 do not. Leukemias from stable transgenic rag2-EGFP-mMyc (A) and rag2-EGFP-bcl-2 embryos injected with rag2-mMyc (D) were transplanted into irradiated recipient fish (B-C, E-F). After local infiltration of leukemic cells into the abdomen adjacent the site of injection (B, E), fish were treated with γ-irradiation (23 Gy) and analyzed 3 days after treatment (C, F). Anterior to the left and dorsal toward the top. Panels B, C, E, and F show abdominal views of transplant recipient fish. IR, irradiation.