Figure 5.

Additional factors are critically involved in bortezomib-induced apoptosis of BRCA1-depleted cells. (a) qRT-PCR validation of differentially expressed genes initially identified by a microarray analysis in the course of bortezomib treatment (10 nM) with or without BRCA1 depletion. (b) Western blot showing a bulk of ubiquitinated proteins accumulated after exposure to 10 nM bortezomib in BRCA1- but not BRCA2-depleted HeLa cells. (c) PCR analysis showing lack of XBP1 splicing after bortezomib treatment. Tunicamycin treatment is used as a positive control. (d) Western blot demonstrating that knockdown of ERN1 results in a substantial reduction in the amount of cleaved PARP (cPARP) protein in BRCA1-depleted cells treated with bortezomib. The bar graph below shows quantification of cPARP level normalized to the average of β-actin and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) protein levels. (e) Same as (d) for HECW1