CD274 and glioblastoma: Moreover, analysis of PD-L1 expression in different glioblastoma multiforme subgroups (Verhaak et al., 2010 [21]) revealed an increased expression of PD-L1 in mesenchymal tumour samples (p<0.05) (Figure 1B), whereas the lowest PD-L1 expression was found in proneural tumours.