Dysregulated Myc expression is observed in many types of cancer, in line with the known role of this transcription factor in regulating cellular processes such as apoptosis, proliferation and differentiation. Investigating the function of Myc in diverse biological models provides clues to its role in cancer. Menescal et al. analyse a newly identified, unusual version of Myc (myc17) found in the medaka genome, which also contains a conventional, conserved version of Myc (myc20). Although Myc17 lacks protein-regulatory sequences found in other reported versions of Myc, studies of two inducible transgenic medaka lines show that Myc17 is functional and, like other versions of Myc, drives apoptosis and proliferation in vivo. In addition, long-term myc17 induction causes liver hyperplasia. These transgenic medaka lines can be further used to probe the role of Myc in liver tumorigenesis. Page 492

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