Salk scientist Tony Hunter is the recipient of the 2006 Pasarow Award in Cancer Research for his key discoveries of the chemical "switch" that turns healthy cells into cancer cells.
In 1979, Hunter, an American Cancer Society professor in the Salk's Molecular and Cell Biology Laboratory, discovered that a biological process called tyrosine phosphorylation is a chemical "on-off" switch that can trigger the uncontrolled division of cells — the hallmark of many cancers. Discovery of this important signaling mechanism, which proved to be the underlying cause of many types of human cancer, revolutionized cancer research and, ultimately, led to the development of several innovative cancer therapies.
Phosphorylation — the addition of a tiny phosphate ion to a large protein molecule — is a common way in which the body turns on or off proteins such as enzymes. Thus, phosphorylation of proteins in cells, which is often triggered by external stimuli, acts as a signaling mechanism for cells to respond to their environment, and in particular to respond to factors that promote cell proliferation. Hunter discovered that phosphorylation of tyrosine, one of the 20 amino acids found in proteins, governed how cells multiply.