Fig. 2. Expression changes in time course of signal proteins on PERK pathway in HepG2 cells exposed to three different ER-stress inducers.

Whole cell lysates were prepared for phosphorylated eIF2α, ATF4, and CHOP western blotting from HepG2 cells treated for 0∼24 hr with ER-stress inducers (NaF, Tu and Tg). Protein expression during ER-stress inducer treatment for 0∼24 hr was measured by densitometry of the positive band in each western blot, as described in Materials and Methods. Images are representative of three individual experiments. (A) Time-dependent change of phosphorylated eIF2α level. (B) Change of ATF4 protein expression in the left panel, and change of CHOP in the right panel. Each blot lane time point corresponded to the time point of each column group in lower column graph. Data are mean ± SD of three individual experiments. #P<0.05, versus the value of control at 0 hr.