To assess if Mcl-1 regulates ROS generation through a similar up-regulation of anti-oxidants, we treated CIS-resistant/Mcl-1 proficient cells (HCT116 p53−/−) with chemical inhibitors of most major anti-oxidants, including: 3-AT (catalase), 2-MT (superoxide dismutase), and MSA (glutathione peroxidase) with or without doxorubicin. The gene discussed is TPO; the disease is in situ carcinoma.