Fig. 4.

Silibinin induced ER stress response through disruption of Ca²⁺ homeostasis. a Expression of ER stress-related proteins was detected by western blotting with antibodies for Bip, IRE1α, p-eIF2α, eIF2α, ATF4, CHOP and β-Actin was used as a loading control. b ER stress-related mRNAs were detected by RT-PCR with primers for XBP1, Bip, CHOP and GAPDH was used as a loading control. c PC-3 cells were treated with 150 μM silibinin for 24 h with the presence or absence of 2 μM BAPTA/AM. The intracellular Ca²⁺ concentration was determined by the fluorescence of fluo-3/AM with flow cytometry. d Protein expression was analyzed by western blotting. β-Actin was used as a loading control. e Apoptosis was analyzed after treatment of 150 μM silibinin for 48 h with the presence or absence of 2 μM BAPTA/AM by flow cytometry. f The effects of BAPTA/AM on silibinin-induced apoptosis were measured by western blotting. β-Actin was used as a loading control. Data are presented as mean ± SD (n = 3 in each group). ^* p <0.001 vs. the control group