As with senescence induced by inactivation of tumour suppressors, samples from patients with dermal neurofibromas bearing mutated neurofibromin (NF1), which antagonises Ras/MAPK signalling by being a Ras GTPase‐activating protein, tested positive for expression of p16INK4A and for SAβG activity [127]. This evidence concerns the gene NF1 and neoplasm.