eLife assessment
This important study reveals ELF3 as a putative candidate driver of luminal progenitor (LP) transformation. Up-regulation of ELF3 during replicative stress conditions and in BRCA1 deficient cells may permit cell proliferation by suppressing genome instability. While the hypothesis is compelling, the experimental support is still incomplete, as it does not adequately demonstrate the role of ELF3 in LP cells per se. The mechanistic underpinnings by which ELF3 promotes cell tolerance to DNA damage were not fully explored either. With improvements, the work has the potential to enhance our understanding of how BRCA1 deficiency fuels LP transformation and thereby breast tumorigenesis.