Fig. 2

Phosphorylation of extracellular signal-related kinase 2 (ERK2) correlates with FRA-1 Ser265 phosphorylation in basal breast cancer cell lines. a Immunoblot analyses for AKT and ERK phosphorylation in five breast cancer cell lines and tumor explants (a or b) from the indicated cell populations. b Immunoblot analyses for Fos-related antigen 1 (FRA-1), phosphorylated FRA-1 (Ser265), pERK and ERK in a panel of human breast cancer cells (basal A, basal B and luminal) and BRC cell lines. c Quantification of ERK1 (ERK1/α-Tubulin) and ERK2 (ERK2/α-Tubulin) proteins normalized to α-Tubulin or presented as a ratio of ERK2 expression divided by ERK1 expression (ERK2/ERK1). Phosphorylated FRA-1 levels presented normalized to α-tubulin (pFRA-1/α-Tubulin). The average expression from three independent lysates is presented and error bars represent the standard error of the mean. d Immunoblot analyses for FAK and SRC phosphorylation in BRC cell lines and explants. e Immunoblot analyses of FRA-1 phosphorylation in BRC-31 breast cancer cells incubated with vehicle alone (UNT) or treated with SRC family kinase (SFK) inhibitors (25 nM Dasatinib; 6.6 μM PP2), rapidly accelerated fibrosarcoma (RAF) inhibitors (3 μM sorafenib; 3 μM dabrafenib) or mitogen-activated protein kinases (MEK) inhibitors (1 nM trametinib; 1 μM selumetinib) for 24 hours. f The level of phosphorylation of FRA-1 was quantified relative to the loading control α-Tubulin. The data from three independent lysates are plotted normalized to the dimethylsulfoxide DMSO vehicle control, *P < 0.02. Blots (a, b, d, e) are representative of at least three independent sets of lysates and α-Tubulin serves as a loading control. FAK, focal adhesion kinase