To our surprise, analysis of publicly available data from The Cancer Genome Atlas (TCGA) revealed that breast cancer tissues express higher levels of BRCA1, and lower levels of PINK1 and Parkin than normal breast tissues, although the BRCA1, PINK1 and Parkin expressions did not differ significantly among the intrinsic subtypes or estrogen receptor (ER)/ progesterone receptor (PgR)/ human epidermal growth factor receptor 2 (HER2) expression profiles in breast cancers (Fig. 4a, Fig. S4). This evidence concerns the gene ESR1 and breast cancer.