Described is the production of proteins in a host cell. Even more specifically, described are methods for improving expression of two or more proteins in a cells or host cell. The methods are suited for production of, for example, recombinant antibodies that can be used in pharmaceutical preparations or as diagnostic tools. In certain embodiments, provided are methods for obtaining a cell that expresses two or more proteins comprising providing the cell with two or more protein expression units encoding two or more proteins, characterized in that at least two of the protein expression units comprise at least one STAR sequence.