David shares a lab with his wife, Freda Miller, working on how stem cells build and maintain the brain, and discovering drugs that mobilize our stem cells to enhance and repair the injured brain and skin, and to treat childhood cancers. He is best known for co-discovering, as a graduate student, the signalling protein PI3-kinase (Cell 1987) and discovering the Trk/Nerve Growth Factor receptor when his lab was at the NIH (Nature, Science 1990). David, with Freda, founded the biotechnology companies Exogen Neurosciences, Aegera Therapeutics and Reveille Inc. to bring their research discoveries in cancer, nerve degeneration and stem cell fields to the clinic. David moved to Canada 25 years ago, attracted to the promised land of collaboration, great trainees, and perfect weather.