 Plasmids containing the Factor IX gene, along with plasmids with a gene that codes for resistance to methotrexate, were inserted into Chinese hamster ovary cells via transfection.Transfection involves the insertion of DNA into a eukaryotic cell.Unlike the analogous process of transformation in bacteria, transfected DNA is not ordinarily integrated into the cell's genome, and is therefore not usually passed on to subsequent generations via cell division.