Hierarchical clustering of drug-dependent transcriptional alterations in mouse striatum. (a) Microarray results are shown as a heat map and include genes with a genome-wide significance from two-way ANOVA of the drug factor. Colored rectangles represent transcript abundance (Additional file 2) 1, 2, 4 and 8 h after injection of the drug indicated above of the gene labeled on the right. The intensity of the color is proportional to the standardized values (between -2 and 2) from each microarray, as indicated on the bar below the heat map image. Clustering was performed using Euclidean distance according to the scale on the left. Major drug-responsive gene transcription patterns are arbitrarily described as 'A', 'B1', 'B2' and 'B3. (b) Gene cluster analysis using data-mining methods (Table 1). The fold cellular enrichment (2, 5 or 20 in a particular cell population, as reported in Cahoy et al. ) of the selected transcripts in various cell types is indicated by N (neurons), A (astrocytes) or O (oligodendrocytes). Over-representation of transcription factor binding site (TFBSs), as indicated on the left, was identified using the cREMaG database (see Materials and methods). The statistical significance of enrichment is marked as *P < 0.05.