GPX4 and cancer: To address whether viFSP1 may also kill (cancer) cells by targeting FSP1, co-treatment of viFSP1 with pharmacological inhibitors of GPX4 (RSL3 (ref. 36) and JKE-1674 (ref. 37)) or genetic deletion of GPX4 synergistically38,39 induced ferroptosis in a number of human and murine cancer cell lines as well as rat fibroblast (Rat1) and Pfa1 cells overexpressing FSP1 from different species (Extended Data Fig. 5b–h and Extended Data Fig. 6a–j).