is the Renato Dulbecco Chair in Cancer Research, Deputy Director of the Salk Institute Cancer Center and an American Cancer Society Professor in the Molecular and Cell Biology Laboratory at the Salk Institute for Biological Studies in La Jolla. In 1979, through his work on tumor viruses, he discovered a new class of protein kinase that phosphorylates tyrosine. He has spent most of the last 35 years studying protein kinases and phosphatases, and the role of protein phosphorylation in cell proliferation and the cell cycle, and how aberrant protein phosphorylation can cause cancer. His group also works on other types of posttranslational modifications (PTMs), including ubiquitylation and sumoylation, and crosstalk between PTMs. He has received many awards for his work on tyrosine phosphorylation, and is a member of several academic societies including the US National Academy of Sciences and the Royal Society of London.