Fig. 5

ER stress is involved in CPA induced CHOP protein up-regulation in prostate cancer cells. DU145 cells were treated with the indicated concentrations of CPA for 6 h a or 50 μM CPA for the indicated times b. c and d DU145 cells were pretreated with 5 mM ER stress reducer 4-PBA for 1 h, and then treated with 50 μM CPA for 6 h c or 30 h d. Cells were harvested and subjected to western blot analysis. β-actin was used as a loading control and the indicated protein level in control cells without treatment was set as one. Data shown are means ± S.E. (n > 3) with * p < 0.05, ** p < 0.01. Insets: Representative western blot images of CHOP, DR5 and β-actin