Gregg Leonard Semenza (born July 1, 1956) is an American professor of pediatrics, radiation oncology, biological chemistry, medicine, and oncology at the Johns Hopkins University School of Medicine. He is the director of the vascular program at the Institute for Cell Engineering. He is a 2016 recipient of the Lasker Award for Basic Medical Research. He is known for his discovery of HIF-1, which allows cancer cells to adapt to oxygen-poor environments. Semenza was born in New York City.