The downregulation of miR-126 that we have observed in the ER+ BC tissues is consistent with the results of a study that quantified a panel of miRNAs and showed that miR-126 is downregulated in BC tissues and their matched sera and showed a high correlation with the ER or PR expression levels, but showed no correlation with the age groups (<48 years and ≥48 years) [23]. Here, ESR1 is linked to breast cancer.