The present invention may be included in the field of biotechnology and it covers the improved production of recombinant proteins in insect cells or insect larvae as biofactories by a novel expression cassette. This expression cassette comprises nucleic acid sequences such as promoters, homologous regions (hr) as enhancers, and sequences encoding transcriptional regulators, for example, the baculovirus Ac-ie-01 cDNA, or any combination thereof, which are able to increase the quality and production efficiency of the recombinant proteins. Moreover, the present invention is also directed to the vectors themselves comprising the above mentioned nucleic acid sequences of the invention, cells or insects infected, transformed or transfected with those sequences or vectors, and methods for producing the recombinant proteins by using the aforesaid sequences, vectors, cells or insects.