Synergistic effect of oncogenic forms of myc and ras myc 100 80 ras 60 40 myc t ras 20 50100150200 Age(days)Synergistic effect of oncogenic forms of myc and ras 100 80 60 40 20 0 i D D Tumor-free m ce (%) myc ras myc + ras 0 50 100 150 200 Age (days)