Insertion of DNA sequences into the human chromosomal β-globin locus by homologous recombination

Abstract
A ''rescuable'' plasmid containing globin gene sequences allowing recombination with homologous chromosomal sequences has enabled us to produce, score and clone mammalian cells with the plasmid integrated into the human .beta.-globin locus. The planned modification was achieved in about one per thousand transformed cells whether or not the target gene was expressed.