CDKN2A and neoplasm: The complete genomic loss of the CDKN2A locus together with ablation of p14ARF and p16INK4A expression in both tumours (Figures 1b and 2c) is consistent with the observations in p14ARF-hemizygous mice, whereby loss of the residual wild-type ARF was observed to accompany tumour development.9 Interestingly, p21 and MDM2 were also undetectable in the MPNST with only p53 staining positive in the tumour, unlike the strong presence of all the three proteins in his laryngeal SCC.