Cluster analysis of expression profiles of 45 estrogen-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.