List of genes showing unique cluster-patterns. Based on hierarchical clustering of 346 genes expressed specifically in either ES, TS, MEF, or in stem cells, we could identify five distinct clusters: Clusters A and E are for extraembryonic cell-lineage-specific clusters; B is for an E8.5 stage-specific cluster; C is a low expression cluster; D is for preimplantation embryo-specific cluster. Lists of genes in these clusters are shown. Cluster 4 in k-means analysis indicates that the gene is ES cell-specific, number 7 is for TS cell-specific, 14 is for MEF-specific, and 12 is for genes commonly expressed in both ES and TS cells.