Fig. 1.

Cells without Ire1 or calcineurin have increased sensitivity to ER stress. a ER stress impairs cell growth: cnb1∆ and ire1∆ cells have impaired growth on tunicamycin, DTT, or the misfolded protein CPY*. Serial dilutions of cells were spotted on plates. b Cell death is induced by ER stress. cnb1∆ and ire1∆ cells have increased susceptibility to ER stress-induced death, as determined by colony plating assay after treating mid-log cultures with 0.5 µg/mL tunicamycin for 5 h. Viable cells expressed as a percentage of untreated cells +/− standard error of the mean (SEM); n = 3. c ER stress-induced death is associated with ROS accumulation. Wild-type, cnb1∆ and ire1∆ cells treated with tunicamycin (0.5 µg/mL) for 5 h were stained with DHE. Fluorescence was imaged at identical exposure times for all samples, and quantitated by counting cell numbers displaying DHE staining throughout the entire cell out of 50 cells using ImageJ software; n = 3.