The neurofibromas found in NF1 patients contain not Schwann cells and a progenitor-like Schwann cell population that initiates neurofibroma, but also fibroblasts, macrophages, mast cells, and other immune cells, and axons. The Ratner lab uses cell culture and mouse models together with gene expression analyses to define the roles of specific cell types in neurofibroma initiation and neurofibroma growth.