VEGFA and renal cell adenocarcinoma: One possible cause of anti-angiogenic therapy resistance is the switch of the angiogenic phenotype: VEGF to PDGF in renal cell cancer, VEGF to FGF in squamous cancers, VEGF to Bv8 peptide in glioblastoma, VEGF to TGFβ in hepatocellular cancer [71], and VEGF to apelin in lung or breast cancers [72].