Mutations introduced into ɛHS2 minichromosomes. The regions of the minichromosomes containing the ɛ-globin gene (gray rectangles represent exons) and HS2 are shown with HS2 and the proximal ɛ-globin promoter region in an expanded format to indicate the positions of the NF-E2, GATA, and CACCC motifs in these sequences. The sites that are mutated in the various minichromosomes are shown (×) below. H, HindIII; X, XbaI; RV, EcoRV; B, BamHI; RI, EcoRI.