In conclusion, we found that Gal-1 and P-gp were both upregulated in breast tumor tissues and cells and Gal-1 knockdown dramatically improved drug sensitivity of breast cancer cells by reducing P-gp expression through inhibiting the Raf-1/AP-1 signaling pathway, providing a novel evidence that combining the depletion of Gal-1 with drugs PTX or ADR is a potential method for the therapy of patients with breast cancer. This evidence concerns the gene FOS and breast cancer.