Despite the existence of other signaling pathways involved in angiogenesis, VEGF/VEGFRs interaction has been considered as a key regulator and constituted an attractive and central target for the development of anti-angiogenic drugs [18,19,20,21,22], the blockade of VEGF signaling pathway by neutralizing antibodies to VEGF or to VEGFRs, soluble VEGFR hybrids, or inhibitors of VEGFRs tyrosine kinase (RTKi) seems to be ineffective as a monotherapy, and resistance is a common event in cancer patients [23]. This evidence concerns the gene KDR and cancer.