This proposal deals with the effects of carbon dioxide buildup in the production of proteins by mammalian cells. CO2, an oxidation by-product, is known to inhibit cell growth and probably to alter important glycosylation patterns. The impact of CO2 on culture parameters such as rates, clycosylation, apoptosis, etc., and its interaction with other process variables such as pH, osmolality, and ammonia concentration, will be determined. Two CHO cell lines will be used and the impact on three proteins, tPA, IFN-gamma, and a neural cell adhesion molecule (NCAM) will be studied. A mechanism for growth inhibition by CO2 will be sought.