Notably, despite that a mild or transient ER stress was believed to promote cancer cell homeostasis initially under harsh environmental conditions and confer resistance to chemotherapy 22, 23, some recent studies found that uncontrolled ER stress induced by silver nanoparticles (Ag NPs) 24, 25 may stimulate apoptosis by mediated transcription factor CCAAT/enhancer-binding protein homologous protein (CHOP), and inhibit P-gp expression due to increased production of ATP-consuming chaperones, rendering MDR cells more vulnerable to anticancer drugs 26, 27. Here, DDIT3 is linked to cancer.