Leland H. Hartwell

Leland H. Hartwell

Leland Harrison (Lee) Hartwell (born October 30, 1939, in Los Angeles, California) is former president and director of the Fred Hutchinson Cancer Research Center in Seattle, Washington. He shared the 2001 Nobel Prize in Physiology or Medicine with Paul Nurse and R. Timothy Hunt, for their discoveries of protein molecules that control the division (duplication) of cells.

When cells with nuclei divide, they divide in phases called G1 (growth), S (synthesis), G2 (growth), and M (mitosis). Nurse, Hartwell and Hunt together discovered two proteins, cyclin and CDK (cyclin dependent kinase), that control the transition from one stage to another. These proteins are called checkpoints, because they check whether the cell has divided properly. If the cell doesn't divide correctly, other proteins will attempt to repair it, and if unsuccessful, they will destroy the cell. If a cell divides incorrectly and survives, it can cause cancer and other serious diseases.

Working in yeast, Hartwell identified the fundamental role of checkpoints in cell cycle control, and CDC genes such as CDC28, which controls the start of the cycle -- the progression through G1.