ESR1 and breast cancer: Our own work has previously established that ANXA8 protein is not detected in the majority of breast cancers but in a distinct subset of CK5 positive, oestrogen receptor (ER) α and progesterone receptor (PgR) negative breast cancers with poor prognosis and in a high percentage of BRCA1-associated cancers [29], confirming the RNA profiles by Perou et al. [28] and Sorlie et al. [30].