Gremlin 1 belongs to the DAN family of BMP antagonists that includes the head-inducing factor Cerberus and the tumor suppressor DAN. Gremlin 1, Cerberus, and DAN block BMP signaling by binding BMPs, preventing them from interacting with their receptors. Gremlin-1 can bind to and inhibit the functions of BMP-2, -4 and -7. Gremlin-1 has been highly conserved during evolution and is present in soluble and cell-associated forms. Gremlin plays an important role in limb bud development. Vertebrate limb development depends on reciprocal interactions between SHH signaling from the posterior mesenchyme and FGF signaling from a specialized ectodermal structure, the apical ectodermal ridge. Gremlin modulates the FGF/SHH feedback loop, by antagonizing BMP repression of FGF signaling. Also, Gremlin-1-mediated BMP antagonism is crucial for mouse lung and kidney development. Gremlin is highly upregulated in idiopathic pulmonary fibrosis, and has been associated to lung carcinoma and mesothelioma. Gremlin-1 is overexpressed in various human tumors including carcinomas of the cervix, endometrium, ovary, kidney, breast, colon, and pancreas. Also, it has been associated with diabetic nephropathy.