In order to identify the transcriptional targets of CD44-HA interactions mediating breast tumor invasion, we initially employed two molecular approaches: i) subtractive hybridization and microarray analyses, using the two BC cell lines, MDA-MB-231 (highly metastatic cells expressing high levels of CD44) and MCF-7 (weakly invasive BC cells without any noticeable CD44 expression); and ii) The MCF-7 founder cell lines were used to establish the CD44-tet Off inducible system. This evidence concerns the gene CD44 and breast cancer.