CDKN2A and neoplasm: p16 is itself a tumour suppressor; germline mutations at its locus CDKN2A are principally associated with familial melanoma in humans, with some increased incidence of pancreatic cancer, suggesting particular importance in melanocytes (Gruis et al, 1995; Bennett, 2003; Hayward, 2003; Kefford et al, 2004; Gray-Schopfer and Bennett, 2006).