Expression vector for production of recombinant proteins

The present invention relates to DNA plasmids to be used for the production of recombinant proteins. More specifically, the present invention concerns the addition of specific DNA elements to expression plasmids that serve a function as enhancing elements. The outcome is to improve the yields of recombinant protein production. A method of enhancing the transcription of a gene in a DNA construct incorporated into the genome of a eucaryotic host cell, wherein the DNA construct comprises a structural gene for a desired protein or polypeptide in a gene promoter upstream of the structural gene, comprises providing at least one enhancer element comprising the nucleotide sequence TTC TGA GAA upstream of the promoter, and exposing the DNA construct to lactogenic stimuli. An expression vector, a host cell and a transgenic mammal containing the vector are of interest.