Abstract: The invention relates to a kit to be used for the identification of a secretion cassette, which in eukaryotic cells gives rise to a higher level of synthesis/secretion of a protein of interest, the coding sequence of which being flanked by the first and the second set of genetic elements, respectively, compared to the other secretion cassettes present in the kit containing the coding sequence at the corresponding position, as well as to a method wherein the kit is used and the use of said kit, whereby the best secretion cassette will be obtained.

Abstract: Mammalian signal peptides can be used to aid in the secretion of mammalian proteins that are normally not secreted. By inactivating signals normally present in the 3? UTRs of mRNAs encoding proteins that are normally not secreted from mammalian cells, the proportion of such mRNA molecules directed to free and cytoskeletal bound polysomes can be reduced.