Fibrogenesis I. New insights into hepatic stellate cell activation: the simple becomes complex

Hepatic stellate cell activation is a complex process. Paradoxes and contro versies include the origin(s) of hepatic stellate cells, the regulation of membrane receptor signaling and transcription, and the fate of the cells on ce liver injury resolves. Major themes have emerged, including the dominanc e of autocrine signaling and the identification of counterregulatory stimul i that oppose key features of activated cells. Advances in analytical metho ds including proteomics and gene array, coupled with powerful bioinformatic s, promise to revolutionize how we view cellular responses. Our understandi ng of stellate cell activation is likely to benefit from these advances, un earthing modes of regulating cellular behavior that are not even conceivabl e on the basis of current paradigms.