Fig. 5.

Recovery of proteasome CT-L activity after removal of the test agents. Tumor cells were treated with marizomib (●), NPI-0047 (○), or DMSO (▴) for 1 h, after which the cells were washed and incubation was continued in fresh medium without drug. At the indicated times, cells were lysed and CT-L activity was determined. Percentage of inhibition was calculated relative to the amount of proteasome activity in cells treated only with DMSO (0.1% v/v). A, PC-3 cells treated with 4 nM marizomib or 1 μM NPI-0047. B, RPMI 8226 cells treated with 4 nM marizomib or 10 μM NPI-0047. C, RPMI 8226 cell viability was assessed before cell lysis.