GPX4 and melanoma: To investigate whether icFSP1 may also work in the human context, we used a human melanoma cell line (A375) and a human lung cancer cell line (H460), which are known to express substantial levels of FSP1 (ref. 5) and which can survive after withdrawal of radical trapping agents even when GPX4 is genetically deleted (that is, with GPX4 knockout)3,4.