In this episode Dr. Irving Weissman discusses his long-term interests in the immune system, including his early medical education and research training. He details his group's work on leukemia viruses and the discovery of the first mammalian hematopoietic stem cells. Irv also discusses efforts to commercialize these laboratory findings to benefit patients with cancer, including the formation of biotech companies to fractionate circulating cancer cells from blood as well as therapeutically target the "don't eat me" signal CD47. He also discusses views about peer review and NIH priorities for funding.