Figure 1 | Direct and indirect angiogenesis inhbitors. Direct angiogenesis inhibitors, such as endostatin, target the microvascular endothelial cells that are recruited to the tumour bed and prevent them from responding to various endothelial mitogens and motogens. Indirect angiogenesis inhibitors, such as ZD1839 (Iressa), target proteins — such as epidermal growth-factor tyrosine kinase and its products bFGF, VEGF and TGF-, or their receptors, on endothelium — that are expressed by tumour cells. Among its many effects, tumour-cell signalling through this receptor induces the expression of vascular endothelial growth factor (VEGF), TGF- and bFGF, which promotes angiogenesis. bFGF, basic fibroblast growth factor; IL-8, interleukin-8; PDGF, platelet-derived growth factor; TGF-, transforming growth factor-. Please close this window to return to the main article.