Quantifying Lipid Peroxidation in Cells

Lipid peroxidation levels were measured as previously described^{69 (link)}. Briefly, cells were seeded in triplicate in 12-well plates 1 day before treatment, pretreated with or without drugs for 24 h, and/or then irradiated. After the cells were incubated for 24 or 48 h, the cell culture medium of each well was replaced with a fresh medium containing 5 μM BODIPY 581/591 C11 dye (Invitrogen, D3861) for lipid peroxidation measurements and incubated for 30 min in a humidified incubator (at 37 °C, 5% CO₂). Subsequently, cells were washed with PBS and trypsinized to obtain a cell suspension. Lipid peroxidation levels were analyzed by flow cytometry using an Accuri 6 cytometer (BD Bioscience). The gating strategy used for the assay was shown in Supplementary Fig. 9.