SCF-suppressed COUP-TFII expression inversely correlates with increase in γ-globin during erythroid differentiation. CD34⁺ cells cultured in EPO-containing medium for 6 days were stimulated with SCF (50 ng/mL) from day 6 to day 14, and RNA extracted from cells harvested on days 6, 8, 10, 12, and 14 was analyzed by quantitative RT-PCR. (A) Expression levels of COUP-TFII mRNA in EPO versus EPO plus SCF. (B) Expression levels of γ-globin mRNA in EPO versus EPO plus SCF. (C) Expression levels of β-globin mRNA in EPO versus EPO plus SCF. (D) The ratio of γ/(γ + β) globin percentages are shown in EPO versus EPO plus SCF. Results are shown as mean ± SD from 3 independent donors that were analyzed in separate experiments. *P < .05 versus SCF-stimulated cells. **P < .01 versus SCF-stimulated cells.