Bortezomib induces the UPR. EBV⁺ Akata cells were treated with 20nM bortezomib (BZ) and harvested at the indicated time points. Nuclear protein extracts were prepared and subjected to Western blot analysis. Blots were probed for C/EBPβ, ATF4, CHOP10, XBP1(s), ATF6, and ZTA, and for β-actin as a loading control.