TGF-β1 secretion was observed in a panel of ccRCC-derived cell lines (SKRC-7, SHRC-10, SKRC-17, and SKRC-52) while the functionality of the TGF-β1 pathway was confirmed through an observation of increased SMAD reporter activity in ccRCC cells treated with TGF-β1. This evidence concerns the gene TGFB1 and nonpapillary renal cell carcinoma.