Irving Lerner Weissman is a researcher and professor in developmental biology at the Stanford University School of Medicine in Stanford, California. Weissman is also a professor of pathology and Virginia & D. K. Ludwig professor of clinical investigation in cancer at the Stanford University School of Medicine. Weissman studies the biology of stem cells and immune cells and has conducted research in those fields during the late twentieth and early twenty-first centuries. In the late 1980s, Weissman’s team developed methods to identify hematopoietic stem cells, or HSCs, which give rise to the body’s blood and immune cells. Also, in the early 2000s, Weissman also co-authored California’s Proposition 71, which secured three billion dollars in state funding for stem cell research after the federal government restricted human embryonic stem cell work. Weissman’s efforts have demonstrated the therapeutic potential of stem cell transplantation in the treatment of diseases, including blood cancer.