Cytokine that may play an important role during carcinogenesis and metanephric kidney organogenesis, as a BMP antagonist required for early limb outgrowth and patterning in maintaining the FGF4-SHH feedback loop. Down-regulates the BMP4 signaling in a dose-dependent manner (By similarity). Antagonist of BMP2; inhibits BMP2-mediated differentiation of osteoblasts (in vitro) (PubMed:27036124). Acts as inhibitor of monocyte chemotaxis. Can inhibit the growth or viability of normal cells but not transformed cells when is overexpressed (By similarity). Homodimer; can also form homooligomers (PubMed:27036124). Interacts with BMP2; can form higher oligomers with BMP2 (PubMed:27036124). Interacts with SLIT1 and SLIT2 in a glycosylation-dependent manner (By similarity). Highly expressed in small intestine, fetal brain and colon. Expression is restricted to intestinal subepithelial myofibroblasts (ISEMFs) at the crypt base. In subjects with HMPS1, by contrast, GREM1 is expressed, not only in basal ISEMFs, but also at very high levels in epithelial cells (predominantly colonocytes), with expression extending most of the way up the sides of the crypt. Weakly expressed in brain, ovary, prostate, pancreas and skeletal muscle. In brain found in the region localized around the internal capsule in the large subcortical nuclei, including caudate, putamen, substantia nigra, thalamus and subthalamus. Predominantly expressed in normal cells including neurons, astrocytes and fibroblasts. By high glucose through TGFB1-mediated pathways in mesangial cell. Down-regulated in tumor cell lines. The disease is caused by variants affecting the gene represented in this entry. HMPS1 is caused by a duplication spanning the 3' end of the SCG5 gene and a region upstream of the GREM1 locus. This duplication is associated with increased allele-specific GREM1 expression that may cause reduced bone morphogenetic protein (BMP) pathway activity. This mechanism also underlies tumorigenesis in juvenile polyposis of the large bowel (PubMed:22561515). Belongs to the DAN family.