NF1 and plexiform neurofibroma: Likewise, in human tissues, senescent cells were not detected in malignant tumours but were observed in pre-cancerous lesions such as colon adenomas[64-66], benign tumours of melanocytes (naevi) caused by the BRAFV600E mutation[67], and neurofibromas resulting from Neurofibromatosis (NF1) inactivation[68].