Cluster analysis of expression profiles of 131 SWT-responsive probes after treatment with E2 or SWT. Gene expression profiles were obtained after treatment with 100 nM of E2 (EM), 0.0256, 0.256 and 2.56 mg/ml SWT (SL, SM and SH). The results of microarray analysis are shown as values of log2 fluorescent intensity. The branch lengths of the clustering tree reflect the degree of similarity of gene expression. Columns represent the gene expression levels in individual samples; rows represent individual genes. Red and green indicate transcript levels above and below the median for each gene across all samples, respectively. Gene clusters denoted by the bars and letters A and B are groups containing estrogen-induced genes. Gene cluster C is the group containing genes induced by SWT in dose dependent manner but not induced by E2. The gene groups A and C are zoomed and the expression patterns with gene names are shown on the right.