Inhibition of the CT-L subunits leads to rapid accumulation of short-lived proteins. HS-Sultan cells transfected with GFPu were treated with 10 μM carfilzomib (CFZ 10 μM), 0.18 μM CPSI + 0.27 μM IPSI (c + i), 20 nM carfilzomib (CFZ 20 nM), 0.27 μM IPSI (i), 0.18 μM CPSI (c), and DMSO for 1 hour, washed, incubated in compound-free media, and harvested at the indicated times for monitoring fluorescence by flow cytometry. Mean ± SD are shown for 2 independent experiments using 2 separate clones. Two-way analysis of variance was performed and compound treatments resulting in statistically significant differences compared with DMSO treatment group (as determined by Bonferroni post-hoc testing): ***P < .001.