POR and cancer: Further, while overexpression of a genetically engineered cytosol-localized catalase (an enzyme that normally localizes in peroxisomes and catalyzes H2O2 decomposition in peroxisomes) in POR-proficient cells promoted ferroptosis resistance (Yan et al., 2020), another recent study showed that deleting endogenous catalase (and thereby abolishing H2O2 decomposition in peroxisomes) did not affect ferroptosis sensitivity in other cancer cell lines (Zou et al., 2020a), suggesting a cellular compartment- or cell line-dependent role of catalase in ferroptosis protection.