K28. Neurofibromatosis is an autosomal, dominantly inherited condition in which neurofibromas, tumors of the skin and nerves, are caused by mutations of the NF1 gene. NF1 encodes neurofibromin, which normally binds to the Ras G protein and increases its GTPase activity. NF1 mutations found in people with neurofibromatosis include whole-gene deletions, many nonsense and frameshift mutations, and some missense mutations. Which of the following statements about NF1 is most likely FALSE?
NF1 is a tumor suppressor gene.
If a mutant NF1 gene from a neurofibroma is transformed into cells in culture, those cells will proliferate.
Both copies of the NF1 gene will probably be mutated in a neurofibroma cell.
The normal NF1 action on the Ras protein will reduce Ras protein signaling.
Non-tumor cells cells in people with inherited neurofibromatosis will have one mutant and one wild type copy of the NF1 gene.