The MDA-MB-436 human breast cancer derived cell line was purchased from American Tissue Type Collection and cultured according to the manufacturer's instructions. Cells were solubilized in TRIzol LS and RNA was extracted using the Quiagen RNeasy kit. Targets were produced using standard Affymetrix procedures from about 7 ug of total RNA. Human mammary epithelial cells were purchased from Cambrex Bio Science and cultured according to the manufacturer's instructions. Cells were solubilized in TRIzol LS and RNA was extracted using the Quiagen RNeasy kit. Targets were produced using standard Affymetrix procedures from about 7 ug of total RNA.