“…When the three branches of UPR fail to correct the unfolded/misfolded proteins that build up in the ER, ERS happens, so these genes are molecular markers of ERS. GRP78 is a molecular chaperone in the ER and is also a marker for ERS activation ( Liu et al, 2021 ). In the cell culture experiment ( Figure 2 ), the mRNA expression of XBP1, AFT6, and GRP78 genes increased after incubation with sugar, and was suppressed by 4-PBA, an ERS inhibitor ( Tang et al, 2021 ).…”