However, newer studies have shown via single-cell RNASeq that GBM-associated fibroblasts exist and that they render the microenvironment more pro-tumorigenic by recruiting monocytes and promoting their differentiation and polarization into M2 macrophages by signaling through Toll-like receptor 4 (TLR4) and thereby contributing indirectly to the immunosuppressive character of the TIME [44,45,46,47]. This evidence concerns the gene TLR4 and glioblastoma.