CXCL1 and neoplasm: Since CXCL1,2,5 and 8 bind to the chemokine receptor CXCR2 which is associated with neutrophil recruitment to tumours,8 we first confirmed that Cxcr2 is indeed highly expressed in metastasis infiltrating neutrophils (figure 7C) and that CXCR2 expression is not affected by gemcitabine treatment (figure 7D; online supplemental figure S9C).