Fig. 4.

Nrf2 is essential for exemestane to induce phase 2 response and suppress ROS production. (A) Dose-dependent induction of NQO1 by exemestane or sulforaphane in wild-type and Nrf2^−/− MEF cells. Cells plated in 96-well plates were exposed to serial dilutions of exemestane or sulforaphane for 48 h. NQO1 activity was determined in cell lysates. SDs for all determinations were less than 10%. (B) Exemestane suppresses ROS production in wild-type MEF, but not in Nrf2^−/− MEF cells. After 24 h of incubation with exemestane, wild-type and Nrf2^−/− MEF cells were exposed to 20 μM DCFDA for 30 min and then challenged with 500 μM tert-butyl hydroperoxide for 30 min, and fluorescence intensity was measured. Means ± SD are shown.