ERBB2 and breast cancer: Stratifying the breast cancer cohort further by subtype [39] revealed a potential prognostic relevance of DKK3 mRNA expression in tumors of the basal (P < 0.001, Fig 3B) as well as the luminal subtype (P < 0.001, Fig 3D and 3E) but not in HER2-positive carcinomas (Fig 3C).