GPX4 and neoplasm: The expression of enzymes involved in GSH metabolism, including glutathione reductase (GSR), GCLC, GSS, glutaredoxin (GLRX), γ-glutamyltransferase 1 (GGT1), glutathione S-transferase alpha 1 (GSTA1), and glutathione S-transferase pi 1 (GSTP1), as well as three selenoproteins, glutathione peroxidase 1 (GPX1), GPX2, and glutathione peroxidase 4 (GPX4), in tumor and surrounding normal tissue samples from the three lung and three liver cancer patients were examined in duplicate by western blotting (Figure 2A–C).