GREM1 and neoplasm: 2020). Here, we focus on the ability of gremlin, a VEGFR2 ligand, to induce the relocation of the receptor on an advecting EC plasma membrane (Ravelli et al. 2015). Gremlin is a soluble molecule secreted in the tumor microenvironment both by ECs and parenchymal cells (Sneddon et al. 2006). The heparin-binding domain of gremlin (Chiodelli et al. 2011) allows its accumulation in the extracellular matrix (ECM), where it stands as a long-lasting stimulus for ECs.