TGFB1 and renal cell carcinoma: Although the RCC cell lines showed a low expression of the TGFBR2 after treatment with recombinant TGF-β1, we detected the induction of the Smad-dependent pathway by high levels of the phosphorylated Smad2 protein (pSmad2) and the downstream target MMP2 in comparison to untreated RCC cells (Figure 2B, 2C).