High-yield expression system based on transfected mammalian cells for the production of recombinant proteins with complex post-translational modifications. Apart from the available adherent cells, our Institute has the expertise in using the highly sophisticated system of mammalian Expi293F cells which ensures rapid and high-yield protein production from high density suspension culture. The culture's supernatant is filtrated and then concentrated/dialysed by use of tangential flow filtration systems. The subsequent isolation of the recombinant proteins is achieved through chromatographic analysis.