Monoclonal antibodies (MAbs) have radically transformed the treatment of many chronic diseases, mainly in the fields of oncology and autoimmunity. The overwhelming majority of therapeutic MAbs are manufactured from recombinant Chinese hamster ovary (CHO) cell lines. The original CHO cell line was isolated in the 1950s, and since the early 1980s, it has become the workhorse of the biopharmaceutical industry. The CHO-DG44 strain was generated after several rounds of mutagenesis that deleted both copies of dihydrofolate reductase (dhfr) genes by…