Northern blot analysis of p16^INK4a in typical and aggressive mantle cell lymphomas. The aggressive MCL 3858 shows a loss of p16^INK4a mRNA expression. This finding is concordant with the lack of protein expression and the homozygous deletion of the gene in this case (shown in Figs 1 and 3, respectively). The blots were stripped of the p16^INK4a probe and rehybridized with the 28S probe as a loading control.