Described is a method for producing a protein of interest, the method comprising: a) providing a recombinant adenoviral vector comprising nucleic acid encoding the protein of interest under control of a promoter, wherein the adenoviral vector has deletions in a first region and in a second region of the adenovirus genome, wherein each of the first region and the second region is required for adenoviral genome replication and/or adenovirus particle formation, b) propagating the adenoviral vector in a first type of complementing cells that express proteins from the first and from the second region of the adenovirus genome so as to complement the deletions of the recombinant adenoviral vector, to obtain recombinant adenovirus particles, c) infecting a culture of a second type of complementing cells with the recombinant adenovirus particles, wherein the second type of complementing cells express protein from the first region of the adenovirus genome but not protein from the second region of the adenovirus genome, to produce the protein of interest, and d) harvesting the protein of interest.