SMAD4 and nonpapillary renal cell carcinoma: Consistent with our previous study in renal tubular epithelial cells,18 the effect of lnc-TSI was independent of other TGF-β/Smads components or regulators, such as TβRI, Sara, Smad2, Smad4, and Smad7,29 since there was no interaction among lnc-TSI and these components or regulators in RNA and protein interaction assay in ccRCC cells (Figure 3A).