HGF and central nervous system cancer: To further validate the functional relationship between Met-expressing cells and macrophages, and to determine their occurrence in distinct glioma niches, we performed a combination of multiplex in situ hybridization and immunostaining on Pdgfbret/ret glioma sections, using probes against Hgf, Aif1 (IBA-1), Fosl1, and Met as well as an antibody against PODXL.