FIGURE 2.

Progressive changes of ER structure under ER stress over time. (A) Immunoblot analysis of p-IRE1 $\alpha$ , IRE1 $\alpha$ , caspase3 (pro and cleaved) and β-tubulin from cell lysates after treatment of HEK293T cells with DMSO or 5  $\mu$ M Tg for the indicated durations. (B) Representative ER structures labeled with GFP-Sec61 $\beta$ (green) in HEK293T cells treated with 5  $\mu$ M Tg for the indicated durations. Yellow arrows point to where initial formation and evolution of an ER whorl occur. Scale bar: 20  $\mu$ m. (C) Percentages of HEK293T cells with ER whorls after treatment with 5  $\mu$ M Tg for the indicated durations. Data were presented as mean ± SD from three independent experiments. (D) 5 $\times$ magnified 3D views of the ring-like ER whorl in the region marked by the red box in the leftmost sub-panel. Scale bar: 10  $\mu$ m.