TNF and glioblastoma: Furthermore, GBM cells transfected with miR-21-5p inhibitor showed a significantly reduced ability to generate M2 GAMs, based on our coculture experiments; this was attributed to the decreased secretion of M2 cytokines such as IL-6 and VEGF by miR-21-5p-silenced GBM cells and an increased secretion of TNF-α, an M1 marker.