A cDNA microarray containing 19,200 ESTs was used to identify genes that may be involved in colon tumor metastasis. RNA from genetically matched Duke's B stage colon carcinoma cell lines KM12C and KM12L4A representing low and high metastatic phenotypes respectively, was reverse transcribed and labeled with Cy3-dUTP (KM12C; green) and Cy 5-dUTP (KM12L4A;red). Genes up-regulated in KM12L4A appear red and those that are down-regulated appear green.