Abstract
The-arrestin adaptor proteins are known to mediate the endocytosis of G protein-coupled receptors. In this way, they down-regulate the activated receptors ensuring that they are degraded or recycled within the cell. As Spiegel explains in his Perspective, it now turns out that-arrestins are also important for the endocytosis and down-regulation of a variety of other receptors including Frizzled 4 and TGF--receptors, II and III ( Chen et al., Chen et al.).