Increasingly, research into the mechanisms by which myostatin controls muscle mass has revealed both new components of this signalling pathway and the participation of parallel pathways in the mediation of myostatin signal. It has been established that myostatin signalling can recruit various intracellular signalling cascades, however it remains unclear how these pathways are intercalated. With respect to new components of myostatin signalling pathway, decorin, a component of the extra-cellular matrix (ECM) has been discovered recently that binds myostatin and modulates its activity. This provides another means by which myostatin signalling can be controlled and raises the question of a potential link between myostatin activity and ECM integrity. Also, the demonstration that other TGF-β related ligands cooperate with myostatin to suppress muscle growth makes the search for manipulating TGF-β signalling pathways attractive.