GPX4 and neoplasm: Further immunohistochemical staining indicated that the ferroptosis inhibitor GPX4 was positively stained in the cytoplasm and nucleus of tumor cells and the immunoreactive score of GPX4 protein was also markedly up-regulated in the DEN model group, which was dose-dependently reduced by the treatment of PZH (all P < 0.01, Fig. 5E and H).