CXCL1 and neoplasm: After 5 weeks of continuous CXCR2 blockade, we could not only observe a marked reduction in tumour vascularization but importantly tumour incidence and overall tumour burden were reduced, suggesting that CXCL1 is crucial for tumour development at early stages in Stat3ΔLep/ΔLep: KrasG12D/+ mice (Fig. 4a,b).