Endoplasmic reticulum stress plays a dual role in ferroptosis, with ATF4 inhibiting ferroptosis by upregulating SLC7A11 in human glioma cells, while ATF4 upregulating ChaC glutathione-specific glutamylcyclotransferase 1 (CHAC1) expression in breast cancer, promoting ferroptosis induced by cystine starvation [142]. The gene discussed is ATF4; the disease is breast cancer.