Spliced HAC1 mRNA is sustained in Ire1-D828A cells upon ER stress. (A) Ire1-D828A cells were treated continuously with Tm for the indicated length of time for HAC1 mRNA splicing on Northern gels and reprobed for the level of KAR2 mRNA. As a comparison, the Tm time course of Ire1-WT cells (Fig 1B) was shown. (B) The percentage of HAC1 mRNA spliced for Ire1-WT (closed square) and Ire1-D828A (closed circle). (C–J) Sustained presence of spliced HAC1 RNA in Ire1-D828A cells even after the removal of Tm and resuspension in fresh media without Tm. (D) The percentage of HAC1 mRNA splicing in cells treated with continuous Tm (closed circle) and in cells recovered after 2-h Tm treatment (open circle). (F, H, and J) Close up of the quantitation for the first 5 h of recovery. Error bars are standard deviations from at least three repeats.