TGFB1 and glioma: Concomitantly, GCM treated microglial cells showed an upregulation in proteins involved in TGFβ signaling pathway such as matrix metalloproteinase 9 (MMP9) and vascular endothelial growth factor (VEGFa) (Figure 2A, 2B), suggesting that glioma-associated microglia exhibit upregulated expression of tumor supportive factors.