Furthermore, distant primary tumours have been shown to induce gelatinase B/MMP-9 in pre-metastatic lung endothelial cell clusters via VEGF receptor-1 signalling, pre-conditioning lungs to metastatic growth, indicating that distant tumours can aggressively determine specific metastatic sites by activating endothelial cells at secondary sites [296,373], in a process involving gelatinase B/MMP-9 expressed by endothelial cells and tumor-associated macrophages that fertilizes the soil necessary for metastatic growth [374]. The gene discussed is MMP9; the disease is neoplasm.