The main goal of this experiment was to contrast the gene expression of mammary gland tissues at three different tumoral stages : M/D-driven mammary gland small tumors vs mammary gland tissues that have been exposed to M/D but they did not develop a tumor (hyperplastic mammary gland) vs mammary gland tissues that were NOT expossed to M/D (normal mammary gland). Expression profile of 18 mice mammary gland tissues at 3 differents neoplastic stages before and after M/D expossure