Indeed, the NF1 heterozygous cells of the microenvironment modulate the growth of pNFs,116 OPGs16 and MPNSTs.107 As the tumour mass can contain up to 50% collagen,48 strategies aimed at targeting the cells that synthesise collagen and extracellular matrix might be required to shrink the bulk of the tumour, in addition to directly targeting the neoplastic cells. This evidence concerns the gene NF1 and neoplasm.