Consistent with this notion of context specificity and potential promiscuity, prior work has suggested neurofibromin may regulate different, or multiple, Ras proteins across different cell lineages: Neurofibromin primarily acts on both HRAS and KRAS in melanoma (28) while KRAS alone is the critical effector in mast cells (29) or glioma (30). The gene discussed is HRAS; the disease is glioma.