GREM1 and cancer: Interestingly Gremlin can induce EMT of tubular epithelial cells and cancer cells (Li et al., 2012; Rodrigues-Diez et al., 2012; Rodrigues-Diez et al., 2014), and can activate other renal cells, including fibroblasts and mesangial cells to increase the production of ECM proteins, such as collagens (Rodrigues-Diez et al., 2012; Huang et al., 2013).