| abstract |
A glutamine-auxotrophic human cell transfected with an exogenous DNA sequence encoding a protein or an exogenous DNA sequence capable of altering the expression of an endogenous gene encoding a protein and an exogenous DNA sequence encoding a glutamine synthetase, wherein these exogenous DNA sequences are located on one or more than one DNA construct, said transfected cell capable of producing said protein and capable of growing in a glutamine-free medium. |