Under the condition of proteostasis in normal cells, the sensors of endoplasmic reticulum (ER) stress, including activating transcription factors 6 (ATF6), inositol-requiring enzyme 1α (IRE1α), and PRKR-like ER kinase (PERK), are in an inactivated state, while in the tumor microenvironment, multiple factors, such as hypoxia (4), abnormal nutrient supply (5), intracellular accumulation of reactive oxygen species (ROS) (6), and low pH (7), can disturb protein folding in ER. The gene discussed is ATF6; the disease is neoplasm.