ESR1 and breast neoplasm: To reveal whether ER-related miRNAs in cell lines could be associated with the ER status in clinical tumors, we used a publicly available dataset from Cimino and colleagues comprising 77 primary breast tumors (53 ER-positive tumors and 24 ER-negative tumors) [29] and determined differentially expressed miRNAs between ER-positive and ER-negative tumors.