KDR and cancer: The discovery and development of specific molecular targets have demonstrated therapeutic potential in cancer treatment, based on signal transduction alterations in cancer cells (6), mostly applying monoclonal antibodies or tyrosine kinase inhibitors that target specific receptors correlated to proliferative pathways like the epidermal growth factor receptor (EGFR) and angiogenesis characterized by the vascular endothelial growth factor receptor (VEGFR) (7).