In the mid-1990s, research supported by the NINDS located the exact position of the NF1 gene on chromosome 17. The gene has been cloned and its structure continues to be analyzed. The NF1 gene makes a large and complex protein called neurofibromin, which is primarily active in nervous system cells as a regulator of cell division and functions as a kind of molecular brake to keep cells from over-multiplying. In addition to work on NF1, intensive efforts have led to the identification of the NF2 gene on chromosome 22. As in NF1, the NF2 gene product is a tumor-suppressor protein (called merlin or schwannomin).