U.S. Patent No. 6,063,630: "Targeted Introduction of DNA into Primary or Secondary Cells and Their Use for Gene Therapy" (Treco et al.;Assignee: Transkaryotic Therapies,inc.)

The present invention relates to a method of gene or DNA targeting in cells of vertebrate, particularly mammalian, origin. That is, it relates to a method of introducing DNA into primary or secondary cells of vertebrate origin through homologous recombination or targeting of the DNA, which is introduced into genomic DNA of the primary or secondary cells at a preselected site. The present invention further relates to primary or secondary cells, referred to as a homologously recombinant primary or secondary cells. The present invention also relates to a method of turning on a gene present in primary cells, secondary cells or immortalized cells of vertebrate origin, which is normally not expressed in the cells or is not expressed at significant levels in the cells.