Characterization of TGF-β1 transfectant clones. TGF-β1 gene transfection was confirmed by RT-PCR and real-time RT-PCR. A, Expression of TGF-β1 and AcGFP1 mRNA was assessed by RT-PCR. Electrophoresis gels (a and b) show the expression of TGF-β1 and AcGFP1 mRNA, respectively. M1 and M2, mock; T1, T2 and T3, TGF-β1 transfectant clone; N, negative control (SCCVII cells). B, Relative levels of murine TGF-β1 mRNA were determined by semi-quantitative real-time RT-PCR. Levels of TGF-β1 mRNA were normalized to those of β-actin mRNA and were found to be significantly higher in TGF-β1 transfectants.