CDO1-induced reduction in ROS detoxification sensitizes breast cancer cells to anthracycline treatment. A, cell viability of doxycycline-induced/not doxycycline-induced CDO1-stable MDA-MB-231 cells before and 48 hours after treatment with different doses of anthracycline (doxorubicin) was measured by MTS assay. Data presented are the mean of 2 independent experiments ± SEM. Group comparisons were carried out using Student t test. *, P < 0.05. B, ROS production, using CM-H2DCFDA probe and cell viability of same cells before and 48 hours after treatment with 0.078 μmol/L doxorubicin was measured. Data presented are the mean of 2 independent experiments ± SEM. Obtained values for A and B were normalized to anthracycline-untreated or -treated doxycycline-induced/not doxycycline-induced empty vector control cells and plotted as % relative to anthracycline-untreated and not doxycycline-induced MDA-MB-231-CDO1-WT cells. Group comparisons were carried out using Student t test. *, P < 0.05; n.s., not significant.