ATF4 and esophageal squamous cell carcinoma: Fan C et al. (2016) reported that icariin (20, 40, 80 μM for 12, 24, 36 h) dose-dependently upregulated the expression of p-PERK, GRP78, ATF4, p-eIF2α, CHOP and pro-apoptotic protein PUMA and downregulated the expression of anti-apoptotic protein Bcl2 in human EC cells EC109 and TE1 ESCC, ultimately interfering tumor cell adhesion and migration, which were attenuated after inhibition of ERS by eIF2α siRNA.