In the tumor microenvironment, excessive cholesterol consumes CD8+ T cells by regulating the expression of X-box binding protein 1 (XBP1), which in turn activates a series of endoplasmic reticulum stress related pathways that impair the function and induce apoptosis of CD8+ T cells and promotes the immune escape of tumor cells [81]. The gene discussed is XBP1; the disease is neoplasm.