The angiogenic and invasive mechanisms of matrix metallopeptidase 9 (MMP-9), vascular endothelial growth factor (VEGF) and Bv8 (prokineticin) have been previously described.17,18 It is thought that neutrophils may drive angiogenesis in malignancy by providing a significant source of MMP-9 which acts to release VEGF from the extracellular matrix (ECM).19,20 In addition to roles in angiogenesis, MMP-9 is also postulated to aid the direct invasion of tumour cells via degradation of ECM/basement membrane. The gene discussed is MMP9; the disease is neoplasm.