A Immunoblot of endogenous BiP resolved by native-PAGE from lysates of CHO-K1 S21 wild-type (wt) or FICD-/- cells either transiently overexpressing wild-type FICD (high expression level; Hi) or mutant FICDE234G (E/G) or stably expressing recombinant wild-type FICD (low expression level; Lo). The cells in lanes 1-4 were mock transfected. Where indicated cells were exposed to cycloheximide (CHX; 100 µg/mL) for 3 h before lysis. Unmodified ('A') and AMPylated ('B') monomeric and oligomeric (II and III) forms of BiP are indicated. Immunoblots of the same samples resolved by SDS-PAGE report on FICD, total BiP and eIF2α (loading control). Data representative of four independent experiments are shown. 