Figure 3. CFE inhibits TPA-induced AP-1 activation in MCF-7 cells. (A) MCF-7 cells were pretreated with CFE for 1 hour and then stimulated with TPA for 15 minutes. The expressions of p-p38, p38, p-JNK, JNK, p-ERK and ERK were analyzed by using Western blotting. (B) Cells were pretreated with CFE for 1 hour before TPA treatment. After stimulation with TPA for 3 hours, the cell nuclear extracts were obtained and subjected to Western blotting to determine the nuclear levels of NF-κB (p50 and p65) and AP-1 (p-c-Jun) subunits. (C) AP-1 DNA binding activity was determined by electrophoretic mobility gel shift assay.

CFE=Crotonis fructus extract; TPA=12-O-tetradecanoylphorbol-13-acetate; AP-1=activator protein-1; p=phosphorylated; JNK=c-Jun N-terminal kinase; ERK=extracellular signal-regulated kinase; NF-κB=nuclear factor-κB; PCNA=proliferating cell nuclear antigen.