ESR1 and breast neoplasm: In fact, the level of miR-183 was lower in estrogen receptor (ER)-positive breast tumors compared to ER-negative tumors, and higher in human epidermal growth factor receptor-2 (HER2)/neu-receptor-positive tumors compared to HER2/neu-receptor-negative tumors [12], suggesting the roles of miR-183 in different breast cancer cells are different.