Figure 5.

RTA inhibits tunicamycin (Tm)-induced phosphorylation of IRE1 in HeLa cells. Cells were serum-starved for 2 h prior to treatment with RTA (1 μg/mL) ± Tm (2.5 μg/mL) or Tg (1 μg/mL) for 4 h or with RTA (1 μg/mL) for 4 h with DTT (2 mM) added over the last 30 min of treatment. Cell lysates (50 μg) were analyzed by SDS-PAGE. Membranes were immunoblotted with phospho-IRE1 antibody then stripped and reprobed for total IRE1. A representative blot is shown in panel A; (B) Data were analyzed by densitometry. Phospho-IRE1 was corrected for loading using total IRE1. Bars represent mean ± S.E. of 5 experiments. Data were analyzed by paired two-tailed t-test. * P < 0.05 indicates different from Tm alone.