XBP1 and hepatocellular carcinoma: Alternatively, the activation of CHOP or ASNS in neurons may not be entirely dependent on the PERK pathway, although this would be in contrast with findings in human hepatoma cells [35], in which transcriptional induction of the ASNS gene during the unfolded protein response requires the PERK but not the ATF6 and IRE1/XBP1 arms of the stress pathway.