Biomedical research the National Institutes of Health deemed "not worthy of pursuit" in 1980 earned Mario Capecchi a Nobel Prize last month.

Despite the early setback, the Harvard-educated genetics professor persisted toward his goal. Within four years, Dr. Capecchi filed another NIH grant proposal, this time armed with further evidence of what he had sought to prove, that something called gene targeting was possible in mammals.

The Institutes, in responding to Dr. Capecchi's new request, said, "We are glad that you didn't follow our advice."

Many people feel the same way. Twenty years after his breakthroughs at the University of Utah's School of Medicine, it is clear how far researchers' understanding of human disease has progressed.

Another researcher, Oliver Smithies, who concurrently pursued a similar mission at the University of North Carolina at Chapel Hill, shares the 2007 Nobel Prize in Physiology or Medicine. The prize also belongs to Martin J. Evans of Cardiff University in Wales, who demonstrated that genes from embryonic stem cells can be inherited.

Want to figure out the role of a certain gene in susceptibility to cancer? Or what another gene has to do with aging? Due to Dr. Capecchi's work, genetic modifications in mice make it possible to render selected genes inactive, providing information about their functions.

Genes linked with hereditary conditions can be deactivated, or turned "off," in "knock-out mice." Researchers already can knock out more than 10,000 genes. In case you're not counting. Researchers are halfway to uncovering the function of every gene common among mammals.

Conversely - and here's where it gets really interesting - scientists can intentionally activate these genes. Want to test a developing treatment for anxiety disorders? Trying a new medicine to prevent heart disease? Now an animal model can be engineered to contain the DNA that codes for an anxiety disorder, or heart disease. These research rodents are called "knock-in mice." Literally, the disorder is turned "on."

These discoveries open a new frontier of possibility, destroying flat-world theory. Research is now possible that never was before. Advanced animal models are the wind that makes the sailboat move. They accelerate and navigate the research.

The implications for human health are enormous, clearly worthy of pursuit. Knock-out and knock-in mice have moved researchers into uncharted waters of possibility and promise.

Pathways of many hereditary conditions - including obesity, high blood pressure and Parkinson's disease - can be modeled and studied in a laboratory. Drs. Smithies and Evans recognized the potential of this discovery, using knock-out and knock-in mice to study cystic fibrosis.

This disorder devastates multiple organ systems in 1 in every 3,700 babies born in the United States, shortening their life expectancy to 33 years. Ten million Americans carry the CF gene without ever experiencing its symptoms. But those who live with the disease have serious breathing difficulty, overproduction of mucus, intestinal blockage, liver damage and, finally, premature death.

Gene therapy, though in the early stages of research, aims to knock out human disorder-causing genes, among other functions. Eventually, this could mean knocking out cystic fibrosis and other inherited disorders.

Without Drs. Evans, Smithies and Capecchi, essential health studies could not proceed. These three researchers have blown the doors off laboratory expectations and have earned the Nobel Prize.

Countless others in the research community are employing these and other methods to seek cures and treatments for disorders and diseases. Many of these will never be honored with ticker-tape parades and Nobel prizes. They are nonetheless heroes deserving of our deep gratitude.

It is a "thank you" owed by everyone who believes in the power and promise of biomedical research to advance human and animal health. If we truly treasure life, it should be easy to value the research intended to preserve it. In my book, this noble venture is always worthy of pursuit.