Ferroptosis of testicular spermatogenic cells in adult mice is due to downregulation in the expression of nuclear factor E2–related factor 2 (Nrf2) and glutathione peroxidase 4 (GPX4), and reduction of iron transport protein 1 (FPN1) expression by busulfan, which leads to oligospermia (Zhao et al. 2020). Here, GPX4 is linked to oligospermia.