Hierarchical clustering of protein expression data. The expression patterns of 5 proteins, HGAL, CD10, BCL6, MUM1/IRF4 (MUM1), and BCL2, predicted to be associated with distinct subtypes of DLBCL based on the cell of origin by gene expression profiling studies are shown. Positive staining is indicated as red and the lack of staining as green. Stains that were not interpretable are indicated in white. The branching pattern of the dendrogram reflects similarities in the patterns of reactivity of the antibodies, with short branches denoting a high degree of similarity in expression pattern of the cognate protein across 151 DLBCL cases. HGAL clusters with BCL6 and CD10, associated with a GC phenotype, on one branch of the dendrogram (indicated in orange), whereas MUM1 and BCL2, associated with an ABL phenotype, cluster on a separate branch (indicated in blue).