ESR1 and breast cancer: To explore specificity of the miR-375 increase in MΦ, we cocultured MΦ with various human breast cancer cell lines that differ in their ER expression (ER + cells: EFM-192A, MCF-7, T47D; ER − cells: MDA-MB-468, MDA-MB-231, SKBR3, HCC1937), HMEC, and Jurkat cells for 24 h (Fig. 1k).