Schematic representation of the constructs used in the present study. (A) Schematic representation of the HS2δFLβRL construct used for in vivo reporter analysis. The construct is composed of a single HS2 enhancer, the δ-globin gene promoter wt (HS2δwtLβRL) or the CACCC-containing δ-globin gene promoter (HS2CACCCδFLβRL) driving firefly luciferase and the β-globin gene promoter driving renilla luciferase. (B) Schematic representation of the human β-globin cluster showing the relative location of the five hypersensitive sites (HS) of the LCR, ε, Gγ, Aγ, δ and β-genes. (C) Schematic representation of the δ-LCR construct used for in vivo studies. The construct is composed of mini-LCR containing HS4-HS3-HS2-HS1 sites and the full length CACCC-containing δ-globin gene (CACCCδ-LCR).