Figure 3.
Complete linkage hierarchical clustering of genes that most strongly differentiate the subject clusters (SCs). After establishment of SCs, all genes expressed in the epithelial brushings (total = 19,957) were compared across SCs for differential expression using intergroup Student t tests. Genes differentially expressed to a P value < 10−6 between at least two of the SCs were used to compose a set of “highly differentiating” genes (n = 1,384) shown in the heat map here. Complete linkage hierarchical clustering of this highly differentiating gene set along the y axis of the heat map identified nine clusters of coexpressed genes using a cutline at the fourth division of the hierarchical tree (y axis, left). SCs remain on the x axis. GC = gene cluster.