ATF6 and hepatocellular carcinoma: HCC cells treated with endoplasmic reticulum stress source tunicamycin release exosomes containing a large amount of miR-23a-3p, and up-regulate the expression of programmed cell death protein-1 ligand 1 (PDL1) in macrophages by regulating the PTEN-AKT pathway, and histological expression of endoplasmic reticulum stress markers BiP, ATF6, PERK and IRE1α in human HCC specimens was associated with increased infiltration of CD68+PDL1+ macrophages and poor prognosis of patients (16).