We thus determined these markers and observed that SB-T-101141 could clearly induce elevated intracellular iron and ferrous ion levels as well as the increased MDA level that could be efficiently attenuated by DFOM (Fig. 2H–K), and reduced GSH level (Fig. 2L), but no obvious effect on GPX4 expression in breast cancer cells (Fig. S3I), which is an enzyme to reduce esterification and oxidation of fatty acids and cholesterol hydroperoxides. This evidence concerns the gene GPX4 and breast cancer.