Previous studies have found that dormant tumor cells can upregulate all three major transducers of the UPR, IRE1α, PERK, and ATF6 [67, 158].Moreover, GRP78 has previously been shown downstream of activated p38 and appears to play an important role in inducing drug resistance, which is involved in the maintenance of chemical resistance and stem cell populations in pancreatic cancer [152, 158, 159]. This evidence concerns the gene ERN1 and neoplasm.