Prostate tumor and normal samples can be separated into distinct groups. (A) A thumbnail overview of the result of the two-way average-linkage hierarchical clustering of 38 arrays (columns) and 1532 isoforms (rows), as described in ref . (B) Zoom-in view of the array clustering dendrogram. The two array clusters, C1 and C2, are enriched by normal samples and tumor samples, respectively. Cluster C2 is formed by two sub-clusters, reflecting differences in tumor percentage and stroma. (C-E) Isoform signatures up- or down-regulated in different array clusters. (F and G) The result of SVD. (F) The percentage of variation (y-axis) captured by each principal component (x-axis). (G) The low dimensional projection of arrays in the 3D space spanned by the first three principal components. SVD identified the same hierarchical structure as revealed by hierarchical clustering.