PGF and neoplasm: Tumour cells have been shown to secrete a variety of angiogenic factors, including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and placenta growth factor (PlGF) and thereby induce the local formation of new blood capillaries (Kandel et al, 1991; Ferrara et al, 1992; Dvorak et al, 1995).