Ren B (2018) found that celastrol upregulated the expression levels of p-elF2α and p-IRE1, Bip, ATF4, CHOP, and XBP1s in HCC cells HepG2 and Bel7402, to undergo G2/M-phase cell cycle block, decreased viability, and then induced apoptosis. Here, ATF4 is linked to hepatocellular carcinoma.