Although suggested that these inflammatory cells may be involved in the pathogenesis of neurofibromas in patients with NF1 [9], it was the observation that myeloid malignancies, which occur much more often than expected in children with NF1, frequently exhibit loss of activity of both NF1 alleles in people with NF1 [10, 11] that delivered evidence for the functional importance of neurofibromin in myeloid cells. This evidence concerns the gene NF1 and neurofibroma.