Figure 3.

Deoxyelephantopin (DET) induces oxidative stress and c-Jun N-terminal (JNK)-mediated p21^Waf1/Cip1 protein expression and apoptosis in TS/A cells. (A) Reactive oxygen species generation in DET-treated TS/A cells was quantified by flow cytometry. (B) Immunoblotting of JNK, phospho-JNK, c-Jun, phospho-c-Jun, p21^Waf1/Cip1, cleaved caspase-3 and poly(ADP-ribose) polymerase (PARP) protein expression in TS/A cells with or without pretreatment with N-acetyl-L-cysteine (5 mM) for 1 h followed by DET (2 µg·mL⁻¹) treatment at the indicated times. (C) Expression of phospho-c-Jun in DET-treated TS/A cells (6 h) examined on immunostaining and fluorescent microscopy at 400× original magnification. DET-up-regulated expression of phospho-c-Jun was blocked by JNK inhibitor SP600125 (10 µM). (D) Immunoblotting of DET-induced p21^Waf1/Cip1 expression, activation of caspase-3 and PARP cleavage in TS/A cells blocked by 10 µM SP600125.