Fig. 6.

Both Ire1 and PERK are activated to different extents during plasma cell differentiation, but eIF-2α phosphorylation downstream of PERK is blocked. a. Cell lysates from I.29 μ⁺ B cells treated with either LPS or Tg for the indicated period time was harvested and then separated on a 10% SDS-PAGE. The membrane was blotted for Ire1 and for Hsc70 as a loading control. b Cytosolic RNA from I.29 μ⁺ cells treated with LPS, or NIH3T3 cells treated with Tg for the indicated period of time was harvested and separated. Total XBP-1 (tXBP-1) and GAPDH mRNA levels were then probed, the latter as a loading control. RT-PCR was also performed with the same RNA samples using primers specific for the spliced form of XBP-1 (sXBP-1). c Cell lysates from I.29 μ⁺ cells treated with LPS or Tg for the indicated period of time were separated on a 8% SDS-PAGE which was then blotted for PERK, total and phosphorylated form of eIF-2α