Triple Express nonlytic insect-based protein expression system combines an expression cassette (engineered from the silk moth cytoplasmic actin A3 gene, a strong constitutive cellular promoter), an enhancer element and a transcriptional activator that enhances the production of recombinant proteins. Protein quality is improved through reduced degradation and consistent post-translational modifications. The system is amenable to both transient and stable production, and it can be used for both small- and large-scale expression of membrane, cytoplasmic and nuclear proteins.