TGFB1 and renal cell carcinoma: After transfection of lentiviral vector and CD151 being knocked down, Caki-1 and Caki-2 cells were stimulated with recombinant human transforming growth factor-beta 1 (Rh TGF-β1) to elevate the protein level of TGF-β1 to testify if RCC cellular behavior could be rescued by restoring TGF-β1 expression.