Previously, CD45 has been used to distinguish between resident microglia (CD45low) and infiltrating macrophages (CD45high) (41), and in combination with CD11b, microglia and macrophages in rodent and human GBM can be defined as CD11b+/CD45low and CD11b+/CD45high populations, respectively (42). Here, ITGAM is linked to glioblastoma.