In our study, AMP dose-dependently increased ROS generation in both MCF-7 and MDA-MB-231 breast cancer cells; blocking ROS production by ROS scavenger NAC dramatically attenuated AMP-induced GRP78 and CHOP expression, which are two ER stress markers, suggesting that ROS formation argued for an upstream event of ER-stress induced by AMP. The gene discussed is DDIT3; the disease is breast carcinoma.