摘要 |
The present inventors successfully constructed expression vectors that enable high-level production of foreign gene-derived proteins in mammalian host cells, which comprise a translation-impaired drug resistance gene cistron whose expression has been attenuated by altering the codons to the least frequently used codons in mammals; and a gene cassette which has a cloning site for incorporation of a foreign gene between a highly transcriptionally active promoter and a highly stable polyadenylation signal. |