Stable cell lines are the preferred expression systems for producing recombinant proteins, especially for producing large, complex proteins with post-translational modifications. The most common mammalian cell line used for recombinant protein production is the Chinese hamster ovary (CHO) cell line. A large portion of recombinant biopharmaceutical proteins is involved in utilizing CHO-based cell expression systems such as rituximab, epoetin alfa, alteplase, etc. Other mammalian cell lines, such as BHK21, NS0, Sp2/0, HEK293, and HT-1080, have also been reported for use in recombinant protein production.
