Klaus Okkenhaug is Professor of Immunology in the Department of Pathology. He obtained his BSc. in Biochemistry from the University of Victoria, British Columbia, Canada, followed by a PhD. in Immunology from the University of Toronto, where he studied CD28 signalling in Robert Rottapel's lab. In 1999, he moved to London, UK, where he joined Bart Vanhaesebroeck's group at the Ludwig Institute for Cancer Research as a Postdoctoral Fellow, working on the role of the PI3Kδ in immune responses. There he generated the PI3Kδ kinase-dead knock-in mouse, which showed a key role for this PI3K isoform in B cell and T cells. Klaus was a group leader at the Babraham Institute from 2003-2017. Klaus has authored more than 100 per-reviewed publications and has made major contributions to the understanding of the roles of PI3K in immunity, infection and cancer. He has also advised several pharmaceutical companies on the development of specific PI3K inhibitors, some of which are now in use clinically.