The mechanism(s) macrophages used to promote tumour progression are still unknown; however, it has been proposed that macrophages may promote tumour growth and angiogenesis through the production of growth factors and angiogenic inducers such as Epidermal Growth Factor (EGF), vascular endothelial growth factor (VEGF), tumour necrosis factor (TNFα) and Thymidine Phosphorylase (TP) (Xiong et al, 1998; Leek and Harris, 2002). The gene discussed is EGF; the disease is neoplasm.