MSCV-Sox4 and MSCV-Mef2c integrations are present in the same cell in leukemias induced by transplantation of double-transduced cells. (A) Southern blot analysis of HindIII-digested spleen DNA of leukemic animals 6290 and 6654 probed with a neo-specific (left) or a puro-specific (right) probe. (B) Southern blot analysis of EcoRI-digested spleen DNA of leukemic animal 6654 and normal C57BL/6 DNA probed with a BC003479 locus-specific probe (left) or the same DNA digested with HindIII and probed with a Rai1 locus-specific probe (right).