We derived the transcriptional profiles of four invasive and four noninvasive mammary carcinoma cell lines by Affymetrix GeneChip^® Technology with the profile of human mammary epithelial cells as a reference. We focused on the identification of genes which are upregulated in the invasive cell lines based on the following threshold levels: -fold change of 2 or higher in at least three or more cell lines. According to the scoring criteria as described above, we identified 18 transmembrane receptors, 18 secreted proteins and 5 kinases. Several of the genes described have already been put into context with respect to invasion of mammary carcinoma. We therefore focused on deregulated genes for which such an association has not been described before: transmembrane receptor tyrosine kinase DDR2, transmembrane receptors PMP22 and EMP3 and cell adhesion molecule N-cadherin. Making use of real-time PCR, consistently increased steady-state levels of mRNAs for these genes were found in an extended panel of invasive and noninvasive mammary cancer cell lines.