PDT triggers cell death independent of ALOXs and ACSL4. a, mRNA level of ALOX15 and ACSL4 in A549 cells treated with PDT (4 h after). b, Effects of different ferroptosis inhibitors on PDT induced cell death in A549 cells. Lip-1 (8 μM), DFO (100 μM), TRO (100 μM), and BAI (100 μM) is incubated 4 h before PDT. c, Cell viability of HT1080 cells transfected with control siRNA (CTR) or the ALOX15-specific siRNA (pre-incubated for 24 h), then treated with PDT or erastin for 24 h. d, Dose-dependent cytotoxicity of erastin in WT (ACSL4+/+) and ACSL4 KO (ACSL4−/−) MEF cells for 24 h and western blotting analysis of ACSL4 expression. e, Dose-dependent cytotoxicity of PDT in WT (ACSL4+/+) and Acsl4 KO (ACSL4−/−) MEF cells (2 min irradiation). f, Effects of ferroptosis inhibitors (8 μM Lip-1, 100 μM DFO, 100 μM TRO, and 100 μM BAI) on PDT-treated A549 cells.