RON/MSP receptor

RON, encoded by the MST1R gene and also called the macrophage-stimulating 1 receptor, is the second member of the MET receptor tyrosine kinase family. It is activated by its sole ligand macrophage-stimulating protein (MSP, also hepatocyte growth factor-like protein), which is generated in the liver and circulates in serum. RON is normally expressed on tissue macrophages, epithelial cells and osteoclasts, supporting innate immunity, wound repair and bone remodeling. In cancer, RON is overexpressed or aberrantly activated in breast, colorectal, pancreatic and lung tumors, promoting epithelial-mesenchymal transition, invasion and resistance to EGFR-targeted therapy. Oncogenic RON variants including splice forms are described. Blocking antibodies against RON have been evaluated clinically in solid tumors.