The proinflammatory cytokines IL1A, IL1B, TNF, and IL-6 and neutrophil chemokines CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, and CXCL8 were significantly upregulated in patients with SS and patients with PG compared with HCs (see Fig E4, A and B in the Online Repository at www.jacionline.org). Here, CXCL5 is linked to synovial sarcoma.