Yes-associated protein 1 (YAP) promotes proliferation and is oncogenic, but Barry et al. have shown that YAP can also limit tissue expansion. Transgenic expression of Yap in the mouse intestinal tract results in increased WNT signalling along with the loss of intestinal crypts. Conversely, loss of Yap during intestinal regeneration resulted in hypersensitivity to WNT, expansion of intestinal stem and niche cells, as well as microadenoma formation. By restricting Dishevelled (DVL) to the cytoplasm, YAP limits the nuclear activity of DVL, which promotes WNT signalling. YAP expression is lost in a subset of aggressive and undifferentiated human colorectal carcinomas.