Hierarchical clustering of gene expression in canine mammary cancer cell lines and macrophages grown as a co-culture. Gene Spring (Agilent, USA) diagrams of gene expression clustering of (A) canine mammary cancer cell lines grown as a co-culture with macrophages and (B) macrophages grown as a co-culture with cancer cells in both microarray experiments (dye-swaps) shows highly repeatable results. Each row represents a single gene, and each column an experimental sample (from the left: at A. panel: CMT-U27, CMT-U309, P114, CMT-W1 and CMT-W2 cell lines grown with macrophages; at B. panel: macrophages grown with CMT-U27, CMT-U309, P114, CMT-W1 and CMT-W2 cell lines). In each sample, the ratio of the abundance of transcripts of each gene to the mean abundance of the gene's transcript, among all the samples is represented by the colour: green squares, transcript levels below the mean; red squares, transcript levels greater than the mean. Colour saturation reflects the magnitude of the ratio relative to the mean for each set of samples. Dendrogram represents similarities in the expression patterns between experimental samples.