Neurofibromin is a large multifunctional protein with a tumour-suppressor function that regulates the RAS pathway; it inhibits the Ras-GTP proto-oncogene system by converting it to Ras-GDP that subsequently becomes able to inhibit “downstream” complex protein systems (RAF/MEK/ERK and PI3K/AKT/mTOR), causing a negative modulation of cell growth. Here, NF1 is linked to neoplasm.