We found that the BMP inhibitor GREM1 is highly expressed in mesenchymal subpopulations of KPC tumours and acts in a paracrine manner to suppress EMT in the epithelial subpopulation, by reducing expression of the EMT-TFs Snail and Slug. Deletion of Grem1 leads to an almost complete switch of cancer cells to a mesenchymal phenotype, with an associated increase in metastatic frequency. The gene discussed is SNAI1; the disease is neoplasm.