Eukaryotic cell culture presents metabolic engineers with opportunities not found in bacterial systems. The cell cycle enables higher order organisms to continually check their growth conditions, taking internal inventory of their general metabolic state before committing to DNA replication or cell division. Cell cycle check points and growth stimuli comprise an intricate feedback loop. Similarly, insulin signaling works to insure cells do not overproliferate when taking advantage of nutrient availability within a developing multicellular organism. However, the insulin signaling pathway is present in Drosophila S2 cells as well as whole flies, and may control growth in cell culture. The work described here exploited the insulin signaling pathway and the cell cycle for enhanced cell growth and heterologous protein expression. By using the relatively new approach of RNA interference (RNAi) gene silencing, key intermediates involved in growth and cell cycling were interrupted. This work demonstrates both the potential of RNAi and the utility of controlling cellular signaling pathways as new and powerful tools in metabolic engineering.