P4HB and glioma: Furthermore, quantitative analysis of the mRNA levels from both data sets showed that, compared with those in low‐grade glioma (LGG) samples (WHO grade II and III), the expression levels of P4HB, TXNDC12 and PDIA5 were significantly up‐regulated in glioblastoma multiforme (GBM) samples (WHO grade IV), whereas that of CASQ1 were down‐regulated (Figure 1C,D).