1. Alt FW, Kellems RE, Bertino JR and Schimke RT (1978) Selective multiplication of dihydrofolate reductase genes in methotrexate-resistant variants of cultured murine cells. J Biol Chem 253: 1357–1370.
2. Bentley WE, Mirjalili N, Andersen DC, Davis RH and Kompala DS (1990) Plasmid-encoded protein: The principal factor in the “metabolic-burden” associated with recombinant bacteria. Biotech Bioeng 35: 668–681.
3. Biedler JL, Chang T, Peterson RHF, Melera PW, Meyer MB and Spengler BA (1983) Gene amplification and phenotypic instability in drug-resistant revertant cells. In: Chabner BA (ed) Rational Basis for Chemotherapy. New York, USA, pp. 71–92.
4. Cockett MI, Bebbington CR and Yarrantin GT (1990) High level expression of tissue inhibitor of metalloproteinase in Chinese hamster ovary cells using glutamine synthetase gene amplification. Bio/Technology 8: 662–667.
5. Hall CV, Jacob PE, Ringold GM and Lee F (1983) Expression and regulation ofEscherichia coli lac Z gene fusions in mammalian cells. J Mol Appl Gen 2: 101–109.