DDIT3 and liver cancer: Interestingly, as cinchonine has been reported to activate ER stress through increasing the expression of GRP78/CHOP in human liver cancer cells especially in HeLa and A549 cells (Qi et al., 2017), we further identified whether cinchonine could stimulate ER stress in Vero CCL81 cells, ST cells and LLC-PK1 cells.