The cartoon represents the consequences of tumor ER stress on components of the adaptive anti-tumor immune response. Under ideal circumstances (left panel), tumor cells and their antigens are picked up by immune cells such as dendritic cells (DC), which in turn instruct T cells (T) to proliferate and eliminate the tumor cells. A different scenario (center panel and right insert) occurs in the growing tumor where tumor micro-environmental factors such as nutrient deprivation or hypoxia create ER stress in tumor cells (TmC). These stressors induce an unfolded protein response (UPR) in tumor cells, which is then transmitted to nearby DC and brainwashes them. Affected dendritic cells no longer coordinate T cells, and impaired T cells no longer proliferate. This inappropriate T cell education hinders the effect of the body's anti-tumor immune response and allows for unrestrained tumor growth.