CXCR1 and neoplasm: For example, IL-8 produced by immunosuppressive cells like cancer cells, mast cells, macrophages, and neutrophils (60–62) can promote TCSCs self-renewal, sphere formation, and tumor initiation capacity by attaching to TCSCs cell surface CXCR1 and CXCR2 via autocrine or paracrine pathways (62).