Basal phosphorylated STAT1 (p-STAT1) occurred only in myeloid cells from PBMC or GBM samples; however, basal p-STAT3 was elevated in CD4+ T, Treg, B, and myeloid cells in GBM compared with healthy donor PBMCs, consistent with suppressive M2-like macrophages (reviewed in ref. 22). Here, STAT3 is linked to glioblastoma.