GPX4 and cancer: The SRF@Fe(III)-COF integrates peroxidase (POD)-like and glutathione oxidase (GSHox)-like activities to facilitate excessive ROS accumulation and decrease the amount of cellular GSH within cancer cells, which decreased the expression of glutathione peroxidase 4 (GPX4) and induced ferroptosis pathways to precisely execute cancer cell, tumor spheroid, and tumor death.