EPΔ578ER-immortalized progenitors differentiate to granulocytes and monocytes upon the removal of estrogen.

Wright-Giemsa–stained cytocentrifuge preparations were prepared from samples of EPΔ578ER progenitors cultured in the presence (A) or absence (B) of estrogen for 5 days. (C) Cell surface staining with FITC-labeled GR-1 (Ly6G), Mac-1 (CD11b), and F4/80 of EPΔ578ER progenitors cultured in the presence or absence of estrogen for 5 days was determined by flow cytometry. Profiles of unstained cells or cells stained with B220 antibody were performed to ensure that observed changes were not due to increased autofluorescence or to nonspecific antibody binding.