Figure 1.

Hierarchical clustering of gene expression data. Depicted are the approximately 1.8 million measurements of gene expression from the 294 microarray analyses of 49 adult and embryonic tissues. The dendrogram lists the tissues studied and provides a measure of the relatedness of gene expression in each sample. Each row represents a single cDNA clone on the microarray, whereas each column corresponds to a separate mRNA sample. The results presented represent the ratio of hybridization of fluorescent cDNA probes prepared from each tissue mRNA samples to a reference mRNA sample (derived from entire E17.5 mouse embryos). These ratios are a measure of relative gene expression in each experimental sample and are depicted according to the color scale shown at the bottom. As indicated, the scale extends from fluorescence ratios of 0.25 to 4 (−2 to +2 in log base 2 units). Gray indicates missing or excluded data. FANTOM, Functional Annotation of Mouse cDNAs.