GAS6 and glioma: Other factors induced in the treated gliomas include scavenger receptor Colec12, which is important in host defense responses, matrix metalloproteinase-2 (Mmp2) and heparanase (Hpse), important for extracellular matrix remodeling and macrophage infiltration [79], Ptpn22, a phosphatase important for macrophage responsiveness, and Gas6, which regulates macrophage phagocytosis (Figure 3A).