Given the fact that LncRNA MIR503HG positively regulates TUSC3 in GC cells, we validated that LncRNA MIR503HG inhibited cell proliferation and epithelial-mesenchymal transition (EMT) in PERK- and IRE1-deficient GC cells, but had little effects on the GC cells with ATF6-deficiency, suggesting that LncRNA MIR503HG inhibited GC progression in a ATF6-mediated UPR dependent manner, and our results were partially supported by the previous work (32–34). This evidence concerns the gene ERN1 and gastric cancer.