This either indicates that brain tumor growth triggers de novo Pdpn expression in the resident microglial compartment or that the CD11b+ PDPN+ population is constituted by infiltrating myeloid cells, in line with the finding of a PDPN+ subpopulation of peripheral myeloid cells (in the mandibular lymph node in tumor-bearing and untreated control mice Figure 1B and Figure S1A). Here, ITGAM is linked to neoplasm.