PDIA4 and glioblastoma: To identify downstream substrates of PDIA4 in GBM cells, we referred to the methods used in previous publications [32, 34], and create stable GBM cell lines expressing the mutant version of PDIA4 containing three mutations from CXXC to Cys-X-X-Ala (CXXA) at the three active sites with the flag tag before the C-terminal KEEL sequence (Fig. 2A).