Insect cells such as Sf21 and Sf9 have become popular research tools in studying viruses and in expressing recombinant protein. Perhaps the most well-known application is the use of the baculovirus expression vector system (BEVS) to transfect insect cells with genes of interest. This method has found widespread use in both academic and industrial settings. Insect growth media, naturally, is crucial to this process. Robust cell growth and protein production will require media with the right formulation. Other requirements such as presence or absence of animal serum may also be an important consideration.