In our previous work (35), we demonstrated that FSHR1 expression in the tumor-associated vasculature of primary ccRCC correlates strongly with clinical response to sunitinib, a VEGFR-targeted tyrosine kinase inhibitor, with high sensitivity and specificity, suggesting that FSHR1 may mark a functional angiogenic endothelium that is more susceptible to antiangiogenic therapy. This evidence concerns the gene KDR and nonpapillary renal cell carcinoma.