EIF2A and esophageal cancer: When we first monitored the PERK-eIF2α pathway in CUDC-907 (30 nM)-exposed esophageal cancer cells, no significant change of p-PERK and p-eIF2α was detected by western blot, suggesting the inactivation of the PERK-eIF2α signal cascade (Additional file 1: Fig. S6d).