Gene list enrichment analysis (Toppgene Suite analysis), showed that differentially expressed genes were classified as “genes upregulated in breast cancer samples positive for ESR1 as compared with the ESR1 negative tumors” such as: ABAT, ANXA9, DACH1, DNALI1, ERBB4, ESR1, EVL, GATA3, GREB1, NAT1, RET, SYT1, and TFF3. This evidence concerns the gene ERBB4 and breast cancer.