It should be noted that Gpx4 knockout mice are embryonic lethal, thereby raising concerns on potential toxicity issues of GPX4 inhibitors for in vivo treatment (Yoo et al., 2012; Angeli et al., 2014); however, some cancers appear to be more sensitive to GPX4 inhibitors compared to their corresponding normal cells (Zou et al., 2019), suggesting that there might exist a therapeutic window for targeting GPX4 in certain cancers. The gene discussed is GPX4; the disease is cancer.