CXCR1 and neoplasm: Finally, the use of UM-SCC-11B and UM-SCC-74B cells transfected with siRNA targeting CXCR1 and CXCR2 (Fig. 2d) further confirmed that removal of CXCR1/2 receptor signaling could sensitize HPV-negative HNSCC tumor cells to the cytotoxic activity of docetaxel in vitro.