The present invention provides a novel method for culturing cells as well as a novel method for producing a recombinant protein by culturing cells at large scale (up to 1,500 L nominal volume and 750 L working volume), whereby an inflated bag provides a sterile, disposable cultivation chamber. The inflated bag is partially filled with liquid cultivation media and cells, and placed into a containment vessel. The containment vessel is positioned onto an orbitally shaken platform. The orbital shaking moves the containment vessel and thus the bag and induces thereby motion to the liquid contained therein (“shake mixing”). This motion (caused by orbital shaking) induces a dynamic force field that ensures cell suspension, bulk mixing, and oxygen transfer from the liquid surface to the respiring cells without damaging shear or foam generation.