Chymotrypsin-like (CT-L) proteasome activity in brain extracts of killifish treated with different proteasome inhibitors. The activity was measured at day 4 after the beginning of treatment. n=8 per sample group; error bars indicate standard deviation. ** p < 0.01, **** p < 0.0001, one-way ANOVA followed by Holm-Sidak's multiple comparisons test. 