^#: the largest group for each pattern of p14arf expression. ^¶: largest group of that table. In all biopsies, a statistically significant (p<0.001) association was found between the distributions of p14arf and MDM2 patterns of expression. Indeed, the majority of biopsies with loss (30 out of 40: 75%) or a nucleolar relocalisation (11 out of 13: 85%) of p14arf expression, also displayed MDM2 high expression. On the opposite, 64% (56 out of 87) of biopsies with p14arf diffuse nuclear staining did not aberrantly express MDM2. The association between p14arf and MDM2 is shown preceding and from the stages of severe dysplasia at which p14arf aberration increases statistically. In stages preceding severe dysplasia, the largest group has diffuse nuclear p14arf expression and low MDM2 expression. In stages from severe dysplasia, the largest group loses p14arf expression and shows high MDM2 expression. The statistical significance of these data could not be calculated due to the small number of samples.