Stephen Sallan's laboratory and clinical research focuses on the genetic heterogeneity and treatment of the most common malignancy of childhood, acute lymphoblastic leukemia (ALL). The researcher strives to understand the reasons for disease recurrence and drug resistance, develop new, more specific therapies, especially for the 20% of children whose leukemia is not cured by current therapies, and conduct all such research in the context of diminishing the toxicity of treatment. Current endeavors expand our investigations to adolescents and young adults with ALL and also extend the laboratory discoveries to other leukemias and lymphomas.