FIG. 5.

UPR target gene expression in cells that lack both XBP-1 and ATF6α. (A) An XBP-1^−/−/ATF6α doubly deficient MEF cell line was generated by transferring siRNA for ATF6α into XBP-1^−/− MEF cells. ATF6α protein was absent in the doubly deficient cells as confirmed by Western blot analysis with anti-ATF6α antibody. (B) Total RNA was isolated from the indicated cell lines that were untreated or treated with Tm for 6 h and subjected to Northern blot analysis. The same blot was hybridized sequentially with BiP, CHOP, Armet, ERdj4, p58^IPK, and Grp94 probes. Ethidium bromide staining of the gel before blotting is shown at the bottom as a loading control.