We showed that ADA3 was predominantly nuclear in ER+ breast cancers, consistent with our previous studies that ADA3 functions as an ER coactivator [10, 11], whereas ADA3 expression was both nuclear and cytoplasmic in ER- breast cancers and this expression pattern correlated with high ErbB2/EGFR status and predicted poor patient survival [17]. Here, ESR1 is linked to breast cancer.