SMAD7 and prostate cancer: Kaur et al. (2005) described that hepatic cancer cell lines refractory to the TGF-β antitumoral properties have lower levels of TAK1 activity (Kaur et al. 2005). Edlund et al. (2003) found that negative TAK1 prostate cancer cell lines had reduced TGF-beta1-induced phosphorylation of p38 and apoptosis, and described how endogenous SMAD7 interacts with TAK1 acting as a scaffolding protein in the regulation of p38 (Edlund et al. 2003). Although TAK1 participates not only in TGF-β signalling but also in many other molecular pathways (Delaney and Mlodzik, 2006).