Use of vectors to confer resistance to antibiotics g418 and hygromycin in stably transfected cell lines.

The development of dominant selection markers to identify eukaryotic cells that have undergone a gene transformation event has greatly facilitated molecular genetic studies in higher eukaryotic cells. Selection schemes based on resistance to antibiotic cytotoxicity (1,2) will be described in this chapter. Other schemes-for example, based on resistance to inhibition of DNA synthesis by methotrexate (1) or mycophenolic acid (1)-are described in other chapters of this book. Prior to the development of dominant selection markers, the use of recessive markers, such as thymidine kinase (TK) or hypoxanthine-guanine phosphoribosyl transferase (HGPT) was limited to a handful of mutant cell lines that were TK (-) or HGPT(-) (5,6). If one wished to transfect a wild-type cell line, one had first to select a recessive mutant derivative cell line and characterize it before proceeding with the experiments of interest. Such restrictions posed a significant barrier to molecular genetic analyses in higher eukaryotic cells.