Unlike this elevation in RNA Pol I activity that we observed in triple-negative breast cancer (TNBC) cells (SUM1315, SUM149), we did not register any noteworthy changes in cell lines representing HER2+ or Luminal subtypes (SKBr3, MDA-MB-453, T47D, and MCF7) following IR. Here, ERBB2 is linked to triple-negative breast carcinoma.