Fig. 4.

Senescent cells induce JNK activation via secreted GMCSF and bFGF

(A-B) Western blotting analysis of the phosphorylation/activation status of Stat3, AKT, ERK and JNK in MDA-MB-231, MDA-MB-468 and MCF-7 breast cancer cell lines co-cultured with medium (None) or young (PD31) or senescent (PD56) BJ cells. (C-D) Western blotting analysis of phosphorylated/activated JNK in MDA-MB-231 and MDA-MB-468 breast cancer cell lines co-cultured with medium (None) or young (PD31) or senescent (PD59) BJ cells, which were incubated with neutralizing antibodies against IgG, GM-CSF (αG, 5 ng/ml), bFGF (αF, 1 ng/ml), or both bFGF and GM-CSF (αG +  αF). (E-F) Western blotting analysis of phosphorylated/activated JNK in MDA-MB-231 and MDA-MB-468 breast cancer cell lines treated with GM-CSF, bFGF or both. (B, D, F) Quantification of the Western blot results presented in A, C and E, respectively, showing expression levels of indicated proteins relative to None (B), None + IgG (D) or Ctrl (F). Densitometric quantification of bands in the Western blots was performed by ImageJ. The signals were normalized to that of actin