about the involvement of signaling Transforming growth factor in tumor development and metastasis. plays a central role in the signaling network that controls morphogenesis, 2. THE BASICS OF growth and cell differentiation in SIGNALING multicellular organisms. The different members of this pleiotropic family of 2. 1. receptor signaling growth and differentiation factors seem to The family of growth factors regulate many processes in human disease consists of more than thirty members in and, in particular, tumor development. humans alone (15, 16). They cluster in Our understanding of how two...