ESR1 and breast cancer: Hence, this study aimed to evaluate the miRNAs expression in various breast cancer subtypes.<h4>Materials and methods</h4>In this study, after total RNA extraction and cDNA synthesis, expressions of miR-577, miR-505-3p, miR-3682-3p, and miR-4661-5p were investigated in 36 breast cancer samples of ER+ and ER- types and compared with 18 normal adjacent tissues by real-time polymerase chain reaction.