In GBM, newly recruited monocytes are differentiated into MDMs and localize to the perivascular niche through a mechanism driven by PDGF-BB secreted by GBM cells, which involves a PDGFRβ-dependent pathway that induces IL-33 expression and secretion by pericytes and CAFs, which then stimulates MDM migration in an ST2 receptor-dependent manner [20]. Here, IL33 is linked to glioblastoma.