GREM1 and colorectal cancer: The ratio of Meflin+ rCAFs and pCAFs that are positive for Gremlin 1, a potent BMP antagonist, is crucial for the outcome of patients with colorectal cancer, and the exogenous manipulation of the balance between Meflin+ rCAFs and Gremlin 1+ pCAFs improves liver metastasis in colorectal cancer [41].