Comparison of all modified clones by PFGE. A single representative clone from each of the modified constructs was grown in overnight culture and mini prep DNA was used for NotI digestion to release the genomic insert. Digested DNA resolved by PFGE clearly shows the increasing reduction in size of the genomic insert of each of the modified clones whilst maintaining the same position of the backbone vector band on the gel. Lane 1, unmodified pEBAC 148β; lane 2, β-globin gene replaced with EGFP-Neo/Kan; lane 3, δβ-globin genes replaced with EGFP-Neo/Kan; lane 4, Aγδβ-globin genes replaced with EGFP-Neo/Kan; lane 5, GγAγδβ-globin genes replaced with EGFP-Neo/Kan; lane 6, ɛGγAγδβ-globin genes replaced with EGFP-Neo/Kan.