On the other hand, TAMs signal the glioma cells through the PDGFB to PDGF receptor alpha (PDGFRα) axis (Additional file 1: Fig. S1c, d), which could trigger downstream phosphatidylinositol 3 kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways. Here, PDGFB is linked to central nervous system cancer.