RESEARCH ARTICLE

ash on ac lac gi pl se through feedback, especially ‘integral ’ feedback, in which of feedback are secreted molecules of the tumor growth Buzi et al. BMC Biology (2015) 13:13 DOI 10.1186/s12915-015-0122-8local feedback most likely operates on the tissue, rather than the organ scale (for example, controlling epithelial Systems Biology, ETH Zurich, Basel 4058, Switzerland Full list of author information is available at the end of the articlecorrections to system behavior grow in magnitude the longer a system’s output differs from a set-point. The idea that feedback is important in tissue growth control is old [3], but only recently has it been shown that one particular form of feedback- in which the differentiated cells at the factor beta (TGF-β) superfamily. The fact that TGF-β family members suppress self-renewal (promoting differ-entiation) in other lineages as well (for example, [9-11]) suggests that this growth control strategy may be wide-spread, although the limited spatial ranges over which growth factors and other secreted signaling molecules act (typically 0.1 mm or less [12-17]) suggest that this type of * Correspondence