MAF1 expression (probe 222998_at*) increased (Mann-Whitney test p-value = 0.0012) in response to trastuzumab treatment in HER2-positive five-year relapse-free survival breast cancer patients (ROC p-value = 2.7 x 10−6, AUC = 0.874), Fig 6B, suggesting MAF1 may be a predictive biomarker in HER2-positive breast cancer. Here, ERBB2 is linked to breast cancer.