BSF 427 cells were washed and transferred into leucine-free medium supplemented with 2H7-leucine (10 μM) plus and minus Genz-644131 (Genz) (15 nM) and/or CHX (50 μg/mL) as indicated for 0, 3, 6, and 12 h. (A) Western blot analysis of prozyme and TbBiP (loading control) and the quantitation of prozyme protein levels normalized to TbBiP and to the no Genz control (–Genz) in graph format. (B) Quantitation of unlabeled (1H-leucine; light) prozyme per 50 μg total lysate by SRM analysis, where the inset shows the same graph with a subset of the axis range. (C) Quantitation of labeled (2H7-leucine incorporated; heavy) prozyme per 50 μg total lysate by SRM analysis. Error bars represent SEM of biological replicates, where n = 3 except for +Genz +CHX at 0, 3, and 6 h, where n = 2.