Figure 2. Differential phosphorylation and recruitment of c-Fos containing complexes to the AP1 site of the Claudin-2 promoter are associated with the changes in Claudin-2 expression following treatment with c-Src family kinase (SFK) inhibitors.

Treatment of human breast cancer cells (MDA-MB-231) (A) or the liver metastatic variant (2776) derived from the mouse 4T1 breast cancer cell line (B) with SFK inhibitors results in enhanced c-Fos phosphorylation (p-c-Fos) and elevated Claudin-2 expression. Diminished c-Jun phosphorylation (p-c-Jun) and total c-Jun levels are observed following treatment of breast cancer cells with SFK inhibitors. Immunoblots for α-Tubulin served as loading controls. (C) Chromatin immunoprecipitation experiments reveal that c-Fos/c-Jun complexes are enriched on the AP1 site within the CLDN2 promoter in MDA-MB-231 breast cancer cells.