... Takeda K, Imamura T, Aoki H, Sampath TK,Enomoto S, Kawabata M, Kato M, Ichijo H &Miyazono K (1999) Roles of bone morphogeneticprotein type I receptors and Smad proteins in osteoblastand ... Erlangen,Germany). Phosphorylation was quantified relative to totalSmad (anti-Smad, Cell Signaling Technology Inc.) or actin(anti-b-actin, Sigma-Aldrich, St Louis, MO, USA). For quanti-fication, ... the case of inhibins, which also belong to theTGFb superfamily, the pro-domains appear to play a role in assembly and secretion [13]. Similarly, an inhib-itory role of the non-covalently attached...