Leading geneticist John Eppig of Jackson Laboratory, Bar Harbor, Maine reported in early 1998 that "One of the most immediate advantages is going to be the area of pharmaceutical production". Drugs made directly from human proteins today are scarce and extremely expensive. As a result of this new technology, mass production of animals that can secrete human proteins in their milk or blood will be widely used to genetically engineer drugs that can offer promise for treating nearly all inherited disorders such as hemophilia, cystic fibrosis and even emphysema.

Barnyard animals such as sheep, goats, cows and pigs are used and made into living factories for producing a variety of vital human proteins that, when missing in a person, cause disease. One application that the scientists are working on today is combining existing gene-targeting technology with the new cloning methods to produce sheep that secrete a protein important for treating emphysema and cystic fibrosis. The idea is to slip a human gene for the emphysema protein into a female sheep's milk gene. Assuming the experiment is successful, the human protein will be made in the milk, from which it can be harvested and purified. Then a herd of identical sheep can be cloned to mass-produce the protein.

Because the human protein is simply not available, people with the lung disease die unnecessarily young in the absence of the protein. Even though it might be expensive to produce this protein at the present, it would be possible to treat patients in the developed world at least for now.

Scientists are also working on producing in sheep the protein called clotting factor 8, missing in many hemophiliacs. Hemophiliacs must take blood transfusions to replace the clotting factor and that is one of the main reasons why they are at risk for infection with HIV. Such an accomplishment would make it possible to eliminate their need for blood transfusions.

Colin Stewart of the National Cancer Institute-Frederick (Md.) Cancer Research Institute and Development Center, says experiments involving cloned animals could greatly enhance the basic understanding of aging and may provide insights into the development of cancer. Stewart says it will be possible to take DNA from animals of all ages and create clones from it. If there are differences between clones made from younger animals and clones made from older ones, it would provide insight into how genes change with age.