An improved system for large scale production of proteins and/or polypeptides in cell culture is provided. In accordance with the present invention, cells expressing the protein or polypeptide of interest are grown in media that comprise a glycolysis-inhibiting substance. Additionally and/or alternatively, cells expressing the protein or polypeptide of interest are grown in media in which glutamine is limited. The use of such a system allows high levels of protein or polypeptide production and lessens accumulation of undesirable metabolic waste products such as lactate. Proteins and polypeptides expressed in accordance with the present invention may be advantageously used in the preparation of pharmaceutical, immunogenic, agricultural or other commercial compositions.