Effect of KLF2 on human β-like globin gene expression in E10.5 yolk sac in β-globin locus YAC transgenic mice. The percentage of globin/GPA mRNA ratio was determined, and statistical analyses were performed as described in the legend of Figure 1. (A) Embryonic ϵ-globin mRNA in KLF2^+/+globin⁺, KLF2^+/-globin⁺, and KLF2^-/-globin⁺ embryos; and (B) fetal γ-globin mRNA in KLF2^+/+globin⁺, KLF2^+/-globin⁺, and KLF2^-/-globin⁺ embryos.