Herein is reported a method for producing a fusion-polypeptide comprising the steps of a) cultivating a mammalian cell comprising a nucleic acid encoding a variant fusion-polypeptide wherein the amino acid sequence of the fusion-polypeptide has been modified by replacing in a pro-fusion-polypeptide the endogenous protease cleavage site between the pro-peptide and the fusion-polypeptide with an exogenous (with respect to the origins of the parts of the fusion-polypeptide) or artificial protease cleavage site, and b) recovering the fusion-polypeptide or fusion-pro-polypeptide from the cell or the cultivation medium and thereby producing the (recombinant) fusion-polypeptide.