Conditional deletion of X-box binding protein 1 (XBP1), the main target of IRE1, in DCs [109] or in CD4+ T helper cells [110] compromised tumor progression in orthotopic murine models while supported T cell proliferation and function at tumor sites, defining a pro-tumoral role for IRE1 through impairment of cancer immunosurveillance. Here, XBP1 is linked to cancer.