The techniques of gene isolation, modification, and transfer into appropriate host cells have
provided a means to understand protein structure and function by enabling the production of
large amounts of proteins that previously could be isolated in only minute quantities, and by
allowing the generation of proteins with specific, designed alterations. The advantages of
using mammalian cells as a host for the expression of a gene obtained from a higher
eukaryote stem from experience that the signals for synthesis, processing, and secretion of …