Effects of Ik6 overexpression on γ- and β-globin genes. On the indicated days, RT-PCR was performed using total RNA extracted from cultured erythroid cells derived from CB and mPB CD34⁺ cells. (A) Expression of γ-globin and β-globin in fetal cDNA erythroid cells on days 10, 13, 17, and 20 is normalized to GAPDH gene expression. Data are mean values (± SEM) for 4 to 7 experiments. *P < .05 using the Wilcoxon test compared with CTRL and EF1 GFP conditions. (B) Relative expression between γ-globin and β-globin in fetal erythroid cells is shown as the mean of 4 to 7 independent experiments. (C) Relative expression between γ-globin and β-globin is shown in adult erythroid cells in which “compressed switch” normally occurs, and was delayed in Ik6-transduced cells.