GIBCO HuMEC Serum-Free Medium is optimized for the culture of human mammary epithelial cells. It is formulated with known concentrations of proteins, growth factors and other supplements, and is consistent lot-to-lot. CDNA microarray studies indicate that culture of human mammary epithelial cells in GIBCO HuMEC Serum-Free Medium yields gene expression profiles comparable to culture in serum-supplemented mammary epithelial cell culture media, allowing for results representative of normal physiological conditions.