Recombinant DNA TechnologyIt was clear to Cohen and Boyer and others that recombinant DNA technology had farreaching possibilities. As Cohen noted at the time, “It may be possible to introduce in E. coli, genes specifying metabolic or synthetic functions such as photosynthesis or antibiotic production indigenous to other biological classes.” The first commercial product produced using recombinant DNA technology was human insulin, which is used in the treatment of diabetes. The DNA sequence that encodes human insulin was synthesized, a remarkable feat in itself at the time, and was transplanted into a plasmid that could be maintained in the common bacterium Escherichia coli. The bacterial host cells acted as biological factories for the production of the two peptide chains of human insulin, which, after being combined, could be purified and used to treat diabetics who were allergic to the commercially available porcine (pig) insulin. In the previous decade, this achievement would have seemed absolutely impossible. By today’s standards, however, this type of genetic engineering is considered common place.