Mice bearing only the deregulated Myc did not develop mammary tumors by 24 weeks after Blg-Cre activation (Fig. 1F), consistent with our previous work using Rosa;LSL-Myc/LSL-MycWAP- or Blg-Cre mice where we found homozygous knockin of Myc at the Rosa26 locus was insufficient to drive tumorigenesis after monitoring for 54 weeks23,32. This evidence concerns the gene MYC and breast cancer.