VHL and nonpapillary renal cell carcinoma: Both primary and metastatic ccRCC tumors are uniquely characterized by the expression of altered biomarkers associated with increased angiogenesis, metastasis, and drug resistance, including deletion and/or mutation of the von Hippel–Lindau (VHL) tumor suppressor gene in the majority of ccRCC tumors, resulting in the stable expression of hypoxia-inducible factors 1α and 2α (HIFs), and vascular endothelial growth factor (VEGF) [15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33].