XBP1 and synovial sarcoma: Staining of patient salivary gland biopsy sections for spliced XBP1 (Figure 2) revealed that SS patients have elevated levels of UPR activation, as evident by the higher percentage of nuclei that are positive for XBP1s within the tissue (CT vs. SS t-test p = 0.025: 4.05 ± 0.45%, n = 7 vs. 9.31 ± 1.31%, n = 19).