qPCR analysis validates gene expression array analysis of virgin mammary epithelial cell gene expression. Data from qPCR analysis of expression of 55 genes in triplicate independent samples of basal/myoepithelial cells, ER- luminal cells and ER+ luminal cells. Each data point is the mean level of expression, ± 95% confidence intervals, across the three samples of that population relative to the comparator sample. A 'round robin' comparison analysis was used as described in the Methods. Genes determined by this method to be characteristic of the comparator population are indicated below each pair of graphs.