PD-L1 pathway analysis in monocytes treated with exosomes and in CD14+ cells from blood and tumor tissue of GBM patients. (A) Western blot analysis of p-STAT3, p-STAT1, p-Akt, β-Actin, Hsp70 in fibroblasts, GSCs, fibroblast- and GSC-derived exosomes. (B) Western blot analysis of PD-L1, p-STAT3, STAT3, GAPDH in monocytes from two donors treated with fibroblast- and GSC-derived exosomes. (C) Densitometric analysis of PD-L1 and p-STAT3 protein expression in monocytes from two donors treated with exosomes. (D) Western blot analysis of PD-L1, p-STAT3, p-STAT1, p-Erk1/2, pJNK, pp70S6K, and GADPH in CD14+ cells from healthy donor blood (n = 3), in CD14+ cells in blood from GBM patients (n = 3), and in GBM-infiltrating CD14+ cells (n = 6).