A U.S. Patent for “Methods of Perfusion Culturing Using a Shake Flask and Microcarriers” was awarded to Genzyme on March 3rd, 2020. The present invention is a method of optimizing a manufacturing process of producing a recombinant protein, the method comprising: providing a shake flask containing a mammalian cell disposed in a first liquid culture medium, wherein the first liquid culture medium occupies about 20% to about 30% of the volume of the shake flask and contains a plurality of microcarriers at a concentration of about 1.0 g/L to about 15.0 g/L; incubating the shake flask for a period of time at about 32.degree. C. to about 39.degree. C…. Learn More