FIG 3.

Isoginkgetin induces ER stress, impairs the unfolded protein response, and results in accumulation of ERAD substrates. (A) Confocal immunofluorescence analysis of HeLa cells treated with 10 μM isoginkgetin stained with antibodies against ubiquitin, 20S proteasome. or UFD1l. (B) Confocal immunofluorescence analysis of HeLa cells treated with isoginkgetin for 24 h, stained with antibodies against Ub and calreticulin (CRT). (C) Quantitative PCR analysis of the relative mRNA expression levels of ER stress genes BiP, CHOP, GADD34, and ATF3 upon treatment with 10 μM isoginkgetin or 10 μM thapsigargin (Thapsi) for 6 h (n = 3). Values that are significantly different by one-way ANOVA test are indicated by asterisks as follows: *, P < 0.01; **, P < 0.005; ***, P < 0.001. (D) Western blot analysis of the protein levels of ATF4, ATF3, and tubulin loading control in HeLa cells upon treatment with 10 μM isoginkgetin for 0 to 6 h.