Figure 5: Biologic pathways in renal cell carcinoma and tyrosine kinase receptors targeted by VEGF signalling pathway inhibitors.

(A) Tyrosine kinase receptors involved in angiogenesis and lymphangiogenesis targeted by VEGF signalling pathway inhibitors. Multiple cellular subtypes, including endothelial cells, pericytes, tumour cells, fibroblasts and endothelial progenitor cells, are implicated in tumour angiogenesis. Signalling through vascular endothelial growth factor receptors and platelet-derived growth factor receptors leads to endothelial cell growth, migration and survival. Tumour lymphangiogenesis is mainly driven through VEGFC/VEGFR3 and PDGF/PDGFR signalling in lymphatic endothelial cells. (B) Biologic pathways and markers in renal cell carcinoma: AKT/PKB = akt/protein kinase B (gene); ERK = extracellular signal-regulated kinase; GF = growth factor; GFR = growth factor receptor; MEK = methyl ethyl ketone.