Dex maintains high expression levels of c-myb, c-Kit, and RBTN2. A culture of erythroid progenitor cells was kept for 2 days in medium containing Epo, SCF, IGF-I, and freon/charcoal stripped serum (depleted from Dex). Thereafter, aliquots of the culture were cultivated in the same medium supplemented with either Dex or ZK 112,993 at 10⁻⁶ mol/L. Total RNA was extracted from untreated cells (day 0) or from cells cultured for 1, 2, or 3 days in GR agonist or antagonist. Total RNA was analyzed on Northern blots, using full-length c-DNA probes of c-myb, c-Kit, RBTN2, and GATA-1. The ethidium staining is shown in the bottom panel as a loading control.