Funding is requested to support the next meeting of the National Neurofibromatosis Foundation International Consortium for the Molecular and Cell Biology of NF1 and NF2 to be held May 23 to 25, 2004 at the Hotel Jerome in Aspen, Colorado. Beginning with the first meeting in 1985, these conferences have provided a regular forum to bring together scientists and clinicians to share their latest research findings and experiences and to form new collaborative ventures. NNFF Consortia have been instrumental in a number of key research accomplishments, including the cloning of the responsible genes, exploration of protein functions, development of animal models, and creation of a network of patients and clinicians to facilitate clinical trials. The rapid scientific progress and subsequent translation to clinical practice has made annual meetings both scientifically productive and necessary. The 2004 Consortium meeting will be an open meeting advertised to the general scientific community. Each of five platform sessions will be co chaired by two experts in the field who will guide discussion of the presented work from invited speakers and selected submitted abstracts. Participation by junior investigators will be encouraged and the organizers anticipate, on the basis of previous Consortium meetings, that a substantial percentage of the speakers will be young investigators. In addition, longer talks by three keynote speakers from outside the NF community will be incorporated into the scientific sessions. Two poster sessions will also be held which will allow investigators to present abstracts not selected for one of the oral sessions. In addition to updating investigators working on NF1 and NF2 on the latest research developments, this meeting will help to identify critical gaps in our knowledge as well as strategies and collaborations to address them and will play an essential role in developing improved therapies for the complications of these disorders with broad implications to the fields of developmental neurobiology and cancer research.