TGFB2 and cancer: PSA has also been demonstrated to activate the small latent form of transforming growth factor-β2 (TGF-β2) (Dallas et al, 2005), one of the isoforms of TGF-β, a potent growth factor that acts as a tumour enhancer once cancer cells have become refractory to its tumour suppressor effects (Massague, 2008).