Activation of the human δ-globin gene promoter by inserting EKLF binding sequences. LUC activity is relative to that of the SV40 promoter. (A) LUC activity of the mutant plasmids transfected into K562 cells and MEL cells. (B) Consensus sequence of the EKLF binding site and the mutation created in each plasmid. Since the EKLF binding site in the β-globin gene does not match well with the δ-globin gene sequence (Fig 1B), 2 segments of the δ-globin gene with partial matches to a CAC box (centered at about −85 and −95) were mutated as indicated and tested for effects on expression. The wt plasmid contains the −612 to +68 bp portion of the δ-globin promoter. *Difference (P < .05) from the wild-type plasmid.