ESR1 and breast cancer: MiR-101 expression was reduced in breast cancer samples of 85.71% (6/7 samples) of triple negative, 62.50% (5/8 samples) of ER/PR+, HER2+, 88.89% (8/9 samples) ER/PR+, HER2− and 83.33% (5/6 samples) of ER/PR−, HER2+, when compared with that in adjacent normal breast tissues, respectively (Figure 1A).