Transgenic overexpression of the BMP antagonist Noggin in intestine or induced whole-body deletion of Bmpr1a can drive hyperproliferative intestinal polyposis, resembling the phenotypes of juvenile polyposis syndrome14, 17, and transgenic expression of Gremlin 1 also initiates intestinal tumorigenesis22. Here, GREM1 is linked to gastrointestinal polyp.