HDN phenotype shifts with tumour stage: in early disease, HDNs exhibit antitumour N1 characteristics, whereas in advanced tumours, TGF-β polarises them into a protumourigenic N2 phenotype, marked by secretion of pro-angiogenic and pro-metastatic factors such as VEGF and matrix metalloproteinase-9 (MMP-9) (11). The gene discussed is MMP9; the disease is neoplasm.