ERBB2 and breast cancer: In breast cancer management, microarray-based mRNA measurements can assess relative levels of different mRNA molecules.58 Several multigene predictor assays, including Oncotype DXTM, MammaprintTM, and TargetPrintTM, have been approved.59 These assays utilize HER2 mRNA associated with other genes related to HER2 amplification, in evaluating recurrence risk of breast cancer.60