Recombinant DNA technology allows scientists to isolate individual genes and insert them into other organisms. This has led to the production of recombinant proteins like human insulin, erythropoietin, and blood clotting factor VIII in microorganisms and cell cultures for medical use. The human insulin gene was isolated and inserted into plasmids in bacteria, which then mass-produced human insulin that could be purified and used as treatment for diabetes without side effects. Similarly, the genes for erythropoietin and factor VIII have been expressed in mammalian cells to produce these proteins for therapeutic purposes. Transgenic plants have also been engineered to produce recombinant proteins like the anti-coagulant hirudin in their tissues.