Fig. 2.

The Ire1, ATF6, and PERK branches of the UPR are intact in I.29 μ⁺ cells. NIH3T3 fibroblasts or I.29 μ⁺ B cells were treated with the ER stressors tunicamycin (Tm) or thapsigargin (Tg) for the indicated period of time. Cell lysates were harvested and separated on 10% SDS-polyacrylamide gels and transferred for western blot analyses. The membrane was then blotted for the PERK targets CHOP and ATF4, the Ire1/ATF6 regulated target, XBP-1(S), and mouse μ heavy chain (which is only present in I.29 μ⁺ cells). Hsc70 was examined as a control for loading. The asterisks indicate two non-specific bands detected with the ATF4 antibody in I.29 μ⁺ cells