The hormone relaxin has long been recognized as important to mammalian reproductive processes (see the Perspective by Ivell), and the development of therapeutics to treat preterm labor disorders and delivery problems has been stifled by the elusiveness of its cognate receptor. Hsu et al. have identified a G protein-coupled receptor that mediates the effects of relaxin. This is somewhat surprising because a structurally similar hormone, insulin, signals through a receptor-type tyrosine kinase.
R. Ivell, This hormone has been relaxin' too long! Science 295, 637-638 (2002). [Full Text]