Figure 4.

Fisetin-induced eIF-2α phosphorylation in HCC cells via the inhibition of the protein phosphatase 1 (PP1)-mediated regulatory system for eIF2α phosphorylation. HA22T, apicidin-R, and SAHA-R cells were treated with fisetin (90 μM) for 24 h. (A) p-eIF2α levels were increased and PP1 expression was decreased in HCC cells upon fisetin treatment. Interestingly, increased PP1 protein expression was noted in apicidin-R and SAHA-R cells compared with HA22T in normal conditions. (B) In Fig. 4A, all protein samples were analyzed by western blotting. The protein expression was normalized to GAPDH. * p < 0.05, ** p < 0.01, *** p < 0.001 compared with the control group.