One of the few genes whose high expression was significantly correlated with this subtype was the HER4 receptor (Figure 5A); high expression of HER4 and average expression of two of its ligands (HB-EGF and NRG1) was observed in this tumor subtype that typically shows low grade, slow growth, and an ER-rich expression signature. This evidence concerns the gene GSTM1 and neoplasm.