A common theme in cancer is the dysregulation of a normal developmental process that either directly causes cells to grow in an uncontrolled manner, or renders them susceptible to cellular damage that, in turn, leads to uncontrolled growth. One example of this process occurs with a normal cellular gene called Notch, which is inappropriately activated in a large fraction of cases of a certain type of blood cancer called T cell acute lymphoblastic leukemia (T-ALL). During normal development of the immune system, regulated Notch activity is required for formation of mature lymphocytes that protect the body from infection. When activated, Notch promotes the formation of normal T lymphocytes, but if this signal is not turned off in time, these T cells can undergo malignant change and become cancerous. Dr. Andrew Weng is studying the signals that are generated by Notch activation and the context in which these signals are received by the cell. By understanding the role of Notch in cancer development, he hopes to develop methods for manipulating Notch activity to shut down the growth of established cancer cells, and perhaps also to prevent it from occurring in the first place.