FIG. 6.

Curcumin inhibits 20S proteasome activities. (A) HeLa cells were treated with DMSO, curcumin (30 μM), or MG132 (5 μM) for 5 h. The activities of 20S proteasome, including trypsin-like, chymotrypsin-like, and PDGH activities, in the cell lysates were measured as described in Materials and Methods. (B) Purified 20S proteasome (100 ng) was used to examine the effects of curcumin (30 μM) and MG132 (5 μM) on proteasome hydrolytic activities. The data are means plus standard deviations; n = 3. *, P < 0.01; #, P < 0.005; δ, P < 0.001 compared to DMSO treatment.