ERN1 and glioblastoma: For example, the use of ursodeoxycholic acid (UDCA) alone or associated with the proteasome inhibitor bortezomib (BTZ) leads to G1 cell cycle arrest and consequent decrease in cell viability by apoptosis in GBM, triggering ER stress through the ATF6-IRE1-PERK axis (Yao et al., 2020).