The activation of TLR9 in GBM seems to promote hypoxia-induced tumour cell invasion, probably due to the CpG-ODN effect and the activation of MMP-2, MMP-9 and collagenase 3 (MMP-13), as shown in U373 and U87 cell lines [127,128,129]. Here, TLR9 is linked to glioblastoma.