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Penn graduate Gregg Semenza was awarded the Nobel Prize for his isolation of the hypoxia-inducible factor complex from cultured liver cells.

Penn graduate Gregg Semenza was awarded the 2019 Nobel Prize in Physiology or Medicine today for his research on how oxygen availability affects cells. 

Semenza graduated with a Ph.D. in genetics from the School of Arts and Sciences in 1984 and a medical degree from the Perelman School of Medicine in 1982. He shares the prize with two other scientists, William Kaelin, a professor at Harvard Medical School, and Peter Ratcliffe, a professor at Oxford University.

The Nobel Committee decided to award Semenza, Kaelin, and Ratcliffe with the honor because of their research on how cells sense and respond to changes in oxygen availability, according to a press release from the committee. Specifically, Semenza isolated the hypoxia-inducible factor complex, or HIF-1, from cultured liver cells. In response to low oxygen levels, the HIF-1 protein binds to the DNA segments that contains the gene for the hormone erythropoietin. Previous research had demonstrated that low oxygen levels lead the body to release more erythropoietin, which leads to the production of red blood cells. 

Semenza said in an interview with the Nobel Prize Committee that he was asleep when the Nobel Assembly called to inform him of the news. He only picked up the phone after the committee called him twice. 

“Even after people have been telling you for 20 years or more that it’s going to happen, no one expects it,” he said in the interview. 

Semenza began studying how oxygen affects cells during his Ph.D. research at Penn, where he studied the β-globin gene. In a paper, Semenza wrote that deficient production of the β-globin gene causes ineffective production of red blood cells that carry oxygen and sometimes leads to anemia, a condition in which the body does not have enough red blood cells. 

Semenza began working as a faculty member at Johns Hopkins Medicine in 1990, where he currently serves as the director of the Vascular Program at the Institute for Cell Engineering. 

Twenty-nine Nobel laureates have been affiliated with Penn — either as graduates or as professors. The last Nobel Prize awarded to a Penn affiliate was in 2011, when former professor Thomas Sargent was awarded the prize in economics.