ABSTRACT 960490 CAGAN Normal fetal development requires a carefully choreographed interplay of many molecules. One of the most important discoveries biologists have made in recent years is that these molecules seem to arrange themselves as pathways or 'cassettes': one cassette of molecules allows cells to communicate with one another while another cassette might direct cell movement. Dr. Cagan's laboratory is studying one of the most widely used cassettes in development, the Notch pathway. The Notch pathway plays a central role in the making of most tissues in a wide variety of organisms, including insects and humans. This includes our immune system, musculature, skin, heart, nervous system, etc. Defects in the Notch pathway have been implicated in leukemias and are undoubtedly involved in a host of other diseases as well. Dr. Cagan's laboratory uses a model system, the developing eye of the fruitfly, Drosophila, to investigate the role of the Notch pathway in development. They are using a variety of tools to understand how the different molecular components of the 'Notch cassette' interact with one another. Abnormal Notch function results in an abnormal eye. By shedding light on this critical pathway in the eye, Dr. Cagan's research will further our understanding both of how the eye is made and how structures of the body are properly assembled.