Tony Pawson has pursued the mechanisms by which cells in the body communicate, and the aberrations in the process that result in diseases such as cancer. In particular, he has focused on the means by which growth factor receptors at the cell surface are linked to their intracellular targets. This led to the identification of the Src homology 2 (SH2) domain, the prototypic protein interaction module that exerts its effects through the selective recognition of phosphotyrosine sites on activated receptors. It is now apparent that modular protein-protein interactions control many aspects of intracellular signaling pathways, and provide a general architecture for organizing cell regulatory systems. Tony Pawson obtained his Ph.D. at the Imperial Cancer Research Fund (now Cancer Research UK), working on retroviral gene expression. He undertook postdoctoral work at the University of California at Berkeley, where he identified a variety of retroviral oncogene products, and provided early evidence for the role of tyrosine phosphorylation in malignant transformation. He moved to the University of British Columbia, Vancouver as a Assistant Professor in 1981, and then to the Samuel Lunenfeld Research Institute of Mt. Sinai Hospital, University of Toronto in 1985, where he was Director of Research (2000-2005). Over the last 20 years he has explored the mechanisms through which signaling networks within the cell are constructed, building on his discovery of the SH2 domain, and the ways in which such networks are utilized to develop functional tissues, as well as the defects in molecular interactions that promote human disease. Dr. Pawson is a University Professor of the University of Toronto and a Distinguished Scientist of the Canadian Institutes for Health Research. He has received many awards, including the Gairdner Foundation International Award, the AACR/Pezcoller International Award for Cancer Research, the Heineken Prize for Biochemistry and Biophysics, the Louisa Gross Horwitz Prize, the Wolf Prize in Medicine, and the Royal Medal from the Royal Society of London. He is a Fellow of the Royal Societies of London and Canada, a Foreign Associate of the National Academy of Sciences (US), and an Associate Member of EMBO. He was recently appointed by Queen Elizabeth II to the Order of Companions of Honour.