Out of 18 samples in cluster 2, again 15 samples were identified as being ER+ (Pearson χ2; P<0.0001), indicating that elevated NF-κB activation is more common in ER− breast tumours, independent of the IBC of non-IBC phenotype and that the frequent activation of NF-κB in IBC is caused by the frequent ER negativity of IBC specimens. Here, ESR1 is linked to breast neoplasm.