The use of DMSO to enhance protein titers has been widely reported in the literature, however, we do not employ this method due to the toxic nature of DMSO as well as the undefined nature of its effects on cells. For certain cell lines, it may be advantageous to reduce the temperature of the cultures from 37C to 32C following transfection to shift the cell’s usage of energy from replication to protein production. Other strategies include the use of compounds such as sodium butyrate to slow cell growth. As always, some of the best ways to improve protein yields are by ensuring that you have healthy cells and a fully optimized protocol encompassing the growth and maintenance of the cells, the DNA complexation reaction and the transfection of the cells themselves. Ensuring that your cells are happy and healthy goes a long way towards ensuring maximal protein titers.