FIGURE 13.

Proteolytic activities of the proteasome in HeLa cells treated or not with pep5-cpp. Proteasome chymotrypsin activity was measured in aliquots of cell lysates containing 20 μg of protein as described under “Experimental Procedures.” A, whole HeLa cells were treated with pep5-cpp (100 μm) for 24 h, and the proteasome activity was measured in the cell extracts. B, the proteasome activity was measured in the HeLa cell extracts in the presence or absence of pep5 at the indicated concentrations. Lactacystin (10 μm) was used as a positive control. NT, not treated; BL, blank. RLU, relative light units. Error bars, S.E.