ERBB2 and breast cancer: Furthermore, patients treated with trastuzumab had a significant increase in MAF1 expression (p = 0.0012) in the five-year relapse-free survival dataset (p = 2.7 x 10−6, AUC = 0.874), suggesting MAF1 can potentially be a predictive biomarker in HER2-positive breast cancer (Fig 6).