Early studies indicated that sunitinib, a popularly used TKI therapy, might inhibit the ccRCC metastasis via suppressing the endothelial cell tube formation34, therefore we were interested in seeing if ERβ-altered endothelial cell tube formation may result in altering the sunitinib sensitivity to suppress the ccRCC cell invasion. This evidence concerns the gene ESR2 and nonpapillary renal cell carcinoma.