Gene Set Enrichment Analysis. Representative enrichment plot resulting from the comparison of the ECM proteomic signature of metastasis (A) or the ECM primary metastatic colon tumor signature (B) with the gene expression data set GSE49355 comprising 20 primary colon adenocarcinoma samples and 19 paired liver metastasis samples. The position of the leading edge is highlighted and the direction of the correlation indicated. The positions of the ECM signature genes along the class comparison for each gene set are indicated by vertical lines. C - D. Heat map shows enrichment of the ECM metastasis signature in metastasis microarray samples (C) and of the ECM primary colon cancer signature in primary colon cancer microarray samples (D). Cells are colored according to the role of those genes in the enrichment based on their rank metric scores (Additional file 5B). Dark yellow cells indicate genes present in the leading edge of metastasis enrichment; dark blue indicates genes present in the leading edge of colon cancer enrichment; light blue indicates genes trending toward the colon cancer phenotype but not part of the leading edge; light yellow indicates genes trending toward the liver metastasis phenotype but not part of the leading edge. Grey cells indicate genes for which the expression level was not determined.