MAPK8 and glioblastoma: In contrast, upregulation of phospho-JNK1/2 levels was observed in both GBM lines 4 h after treatment with γ-irradiation or CBD, alone or, especially, in combination, but with the characteristic difference between these lines: a dramatic increase of phospho-JNK1/2 levels in U87MG cells and less pronounced and variable increase in U118MG cells (Figure 1A).