It was reported that in human pancreatic cancer cells, PERK activation decreases the expression of Hsp90 and Hsp90–Cdc37 chaperone complex suppressed the autophosphorylation of p38.90 Under circumstances of ER stress, in the autophagy-to-apoptosis switching process, activated PERK inhibits the activity of Hsp90–Cdc37 complex to initiate the p38 autophosphorylation. The gene discussed is EIF2AK3; the disease is familial pancreatic carcinoma.