In 1990, as a student in David Baltimore's laboratory at MIT, George Q. Daley demonstrated that a fusion protein called bcr-abl is sufficient to stimulate cell growth and cause chronic myelogenous leukemia (CML). This work helped to identify a class of proteins that become hyperactive in specific types of cancer cells. It helped to lay the groundwork for a new type of drug, attacking cancer at the genetic level: Brian Druker's development of the anti-cancer drug Imatinib (Gleevec), which deactivates bcr-abl proteins. Gleevec has shown impressive results in treating chronic myelogenous leukemia and also promise in treating gastrointestinal stromal tumor (GIST).