Profiling of miRNA expression in tonsillar subpopulations of lymphocytes by microarray hybridization. (A) Unsupervised hierarchical clustering of tonsillar lymphocyte subpopulations using all miRNAs with no more than 50% missing values. (B) Hierarchical cluster of the same samples performed with the classifier of 39 miRNAs obtained after SAM and PAM analysis. Mean centered log ratios for each miRNA are represented. Missing values are in gray. CB indicates centroblast; MC, memory B cell; N, naive B cell; and T, T cell.