The plant cell-based technology used in Protalix's ProCellEx production system offers many important potential benefits over whole plant-based approaches as well as existing mammalian-, bacterial- and yeast-based expression systems currently being used for the development of recombinant therapeutic proteins. Plant cell cultures are grown on aqueous media consisting of highly purified water and defined inorganic nutrients in a completely closed and controlled environment. Protalix's patented bioreactor system utilizes sterilized, large flexible plastic containers for culturing and harvesting cells in consecutive cycles, with a central unit providing oxygen and nutrients. The bioreactors have been designed to allow for the removal of excess air and waste gases, as well as the introduction of inoculants and simple culture media. The entire process is conducted in a GMP (Good Manufacturing Practice) production suite with optimized temperature, lighting, air and nutrient supplies. Because all components of the system are fixed, purification techniques for each specific protein are highly efficient. The production system maintains normal protein assembly and consistent glycosylation patterns with no requirement for additional post-translational modifications, resulting in expressed proteins that maintain their natural biological activity. In addition, the use of plant cell culture presents no risk of mammalian viral transmission.