The mutated GPR85-molecule-induced ER stress in C2C5 cells. (a) Up-regulation of CHOP protein induced by the wild-type and the mutated GPR85. (b) Detection of activation of ER stress markers, CHOP and eIF2α phosphorylation, and activation of caspase-3 by immunostaining (upper panel) and percentages of their positive cells (lower panel). Green, GPR85; red, Chop and eIF2α phosphorylation (p-eIF2α) at 28 h after transfection and activated caspase-3 at 32 h after transfection; blue, Hoechst. Scale bar, 20 μm. The percentage of the cells positive for CHOP, p-eIF2α, and activated caspase-3 in the cells expressing wild-type and the two mutated GPR85. Error bars indicate standard error of the mean (*P < 0.05, **P < 0.01).