CDKN2A and neoplasm: The B-RAFV600Eand N-RASQ61K mutations are also found in up to 80% and 55% ofbenign naevi, respectively [7,8] and benign naevi display several markers of senescence,including positive senescence-associated β-galactosidase (SA-β-Gal) activityand p16INK4a expression [9,10].Although the presence of senescent cells in human benign naevi remainscontroversial [11], accumulating evidence suggests that senescence occurs in vivo and acts as aneffective barrier to tumour formation (Reviewed in [12]).