Induction of UPR genes as a function of reductive stress. (Upper) The β-galactosidase reporter gene was placed downstream from the Kar2 UPR element. The response to increase reductive stress, in the form of exogenous DTT, is observed in wild-type cells (●), the Δfmo strain (▴), and HAC1-deleted (Δhac1) strains (▾). (Lower) Expression of yFMO activity under no stress (solid bars) and in the presence of 2 mM DTT (shaded bars) for the wild-type, HAC1-deleted (Δhac1), and Δfmo strains.