Ways to optimize the cis-acting sequences include adding a highly active enhancer/promoter region, like that in Cytomegalovirus (CMV) immediate early genes; stabilizing mRNAs by adding coding sequence for attachment of a polyadenosine tail; and adding a Kozak consensus sequence or Internal Ribosomal Entry Site (IRES) to the mRNA to optimize its translation into protein. Because each kit comes with a different expression vector, it is essential to become aware of the cis-acting elements in your kit’s vector.