Testosterone treatment upregulates P450 aromatase expression in murine ERα +/+ and ERα −/− male aortic endothelial cells, and increases estradiol release from ERα +/+ cells. Aortic endothelial cells isolated from male ERα +/+ and ERα −/− mice were treated with testosterone (1 nM or 1 uM) for 48 hours. Following treatment, total RNA was isolated and used for qRT-PCR analysis of expression of the P450 aromatase gene. Gene expression levels were normalized to GAPDH and expressed as percent change compared to control (panels A and B). To ascertain the amplification and integrity of the resulting qRT-PCR products, the products were separated on a 2% agarose gel (inset, top panel: P450 aromatase and bottom panel: GAPDH). Cell supernatants were collected following treatment and used for ELISA analysis of estradiol release (panels C and D). Results are expressed as means ± SEM. ** p < 0.01 compared to vehicle control.