Fig. 3. Downregulation of PA28α alters proteasome activity.

a Proteasome fluorogenic peptidase assays of cell lysates from LP1 and RPMI8226 PA28α knockdown and scrambled control stable cells. b LP1 PA28α knockdown stable cells were treated with 10 nM bortezomib for 2 h, cell lysates were obtained, and proteasome fluorogenic peptidase assay was performed to check the chymotrypsin-like proteasome activity, SUC-LLVY-AMC as substrate. c LP1 PA28α knockdown stable cells were treated with serial concentrations of bortezomib, chymotrypsin-like proteasome activity was checked as in b. d LP1 cells were transiently transfected with PA28α siRNA for 72 h, proteasome fluorogenic peptidase assays were performed as in a. **P < 0.01, Student’s t test.