Figure 1. Classification of hepatocellular carcinoma (HCC) based on genome-wide survey of gene expression. A) Hierarchical clustering of 91 HCC tumors. Genes with an expression ratio that had at least a 2-fold difference relative to reference in at least 9 tissues were selected for hierarchical analysis (4,187 gene features). B) Multidimensional scaling (MDS) plot of HCC tissues using 4,187 genes. MDS plotting was based on a matrix of Pearson correlation coefficients from the complete pair-wise comparison of all experiments. The MDS plot displays the position of each HCC tissue in three-dimensional Euclidean space with the distance between HCC tissues reflecting their approximate degree of correlation. Red and green balls represent HCC tissues in cluster A and cluster B, respectively. C) Kaplan-Meier plot of overall survival of HCC patients grouped on the basis of gene expression profiling.